/*
* Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package java.util;
import java.lang.reflect.*;
/**
* This class contains various methods for manipulating arrays (such as
* sorting and searching). This class also contains a static factory
* that allows arrays to be viewed as lists.
*
* The methods in this class all throw a {@code NullPointerException},
* if the specified array reference is null, except where noted.
*
*
The documentation for the methods contained in this class includes
* briefs description of the implementations . Such descriptions should
* be regarded as implementation notes , rather than parts of the
* specification . Implementors should feel free to substitute other
* algorithms, so long as the specification itself is adhered to. (For
* example, the algorithm used by {@code sort(Object[])} does not have to be
* a MergeSort, but it does have to be stable .)
*
*
This class is a member of the
*
* Java Collections Framework .
*
* @author Josh Bloch
* @author Neal Gafter
* @author John Rose
* @since 1.2
*/
public class Arrays {
// Suppresses default constructor, ensuring non-instantiability.
private Arrays() {}
/*
* Sorting of primitive type arrays.
*/
/**
* Sorts the specified array into ascending numerical order.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
*/
public static void sort(int[] a) {
DualPivotQuicksort.sort(a);
}
/**
* Sorts the specified range of the array into ascending order. The range
* to be sorted extends from the index {@code fromIndex}, inclusive, to
* the index {@code toIndex}, exclusive. If {@code fromIndex == toIndex},
* the range to be sorted is empty.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
* @param fromIndex the index of the first element, inclusive, to be sorted
* @param toIndex the index of the last element, exclusive, to be sorted
*
* @throws IllegalArgumentException if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0} or {@code toIndex > a.length}
*/
public static void sort(int[] a, int fromIndex, int toIndex) {
rangeCheck(a.length, fromIndex, toIndex);
DualPivotQuicksort.sort(a, fromIndex, toIndex - 1);
}
/**
* Sorts the specified array into ascending numerical order.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
*/
public static void sort(long[] a) {
DualPivotQuicksort.sort(a);
}
/**
* Sorts the specified range of the array into ascending order. The range
* to be sorted extends from the index {@code fromIndex}, inclusive, to
* the index {@code toIndex}, exclusive. If {@code fromIndex == toIndex},
* the range to be sorted is empty.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
* @param fromIndex the index of the first element, inclusive, to be sorted
* @param toIndex the index of the last element, exclusive, to be sorted
*
* @throws IllegalArgumentException if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0} or {@code toIndex > a.length}
*/
public static void sort(long[] a, int fromIndex, int toIndex) {
rangeCheck(a.length, fromIndex, toIndex);
DualPivotQuicksort.sort(a, fromIndex, toIndex - 1);
}
/**
* Sorts the specified array into ascending numerical order.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
*/
public static void sort(short[] a) {
DualPivotQuicksort.sort(a);
}
/**
* Sorts the specified range of the array into ascending order. The range
* to be sorted extends from the index {@code fromIndex}, inclusive, to
* the index {@code toIndex}, exclusive. If {@code fromIndex == toIndex},
* the range to be sorted is empty.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
* @param fromIndex the index of the first element, inclusive, to be sorted
* @param toIndex the index of the last element, exclusive, to be sorted
*
* @throws IllegalArgumentException if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0} or {@code toIndex > a.length}
*/
public static void sort(short[] a, int fromIndex, int toIndex) {
rangeCheck(a.length, fromIndex, toIndex);
DualPivotQuicksort.sort(a, fromIndex, toIndex - 1);
}
/**
* Sorts the specified array into ascending numerical order.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
*/
public static void sort(char[] a) {
DualPivotQuicksort.sort(a);
}
/**
* Sorts the specified range of the array into ascending order. The range
* to be sorted extends from the index {@code fromIndex}, inclusive, to
* the index {@code toIndex}, exclusive. If {@code fromIndex == toIndex},
* the range to be sorted is empty.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
* @param fromIndex the index of the first element, inclusive, to be sorted
* @param toIndex the index of the last element, exclusive, to be sorted
*
* @throws IllegalArgumentException if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0} or {@code toIndex > a.length}
*/
public static void sort(char[] a, int fromIndex, int toIndex) {
rangeCheck(a.length, fromIndex, toIndex);
DualPivotQuicksort.sort(a, fromIndex, toIndex - 1);
}
/**
* Sorts the specified array into ascending numerical order.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
*/
public static void sort(byte[] a) {
DualPivotQuicksort.sort(a);
}
/**
* Sorts the specified range of the array into ascending order. The range
* to be sorted extends from the index {@code fromIndex}, inclusive, to
* the index {@code toIndex}, exclusive. If {@code fromIndex == toIndex},
* the range to be sorted is empty.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
* @param fromIndex the index of the first element, inclusive, to be sorted
* @param toIndex the index of the last element, exclusive, to be sorted
*
* @throws IllegalArgumentException if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0} or {@code toIndex > a.length}
*/
public static void sort(byte[] a, int fromIndex, int toIndex) {
rangeCheck(a.length, fromIndex, toIndex);
DualPivotQuicksort.sort(a, fromIndex, toIndex - 1);
}
/**
* Sorts the specified array into ascending numerical order.
*
*
The {@code <} relation does not provide a total order on all float
* values: {@code -0.0f == 0.0f} is {@code true} and a {@code Float.NaN}
* value compares neither less than, greater than, nor equal to any value,
* even itself. This method uses the total order imposed by the method
* {@link Float#compareTo}: {@code -0.0f} is treated as less than value
* {@code 0.0f} and {@code Float.NaN} is considered greater than any
* other value and all {@code Float.NaN} values are considered equal.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
*/
public static void sort(float[] a) {
DualPivotQuicksort.sort(a);
}
/**
* Sorts the specified range of the array into ascending order. The range
* to be sorted extends from the index {@code fromIndex}, inclusive, to
* the index {@code toIndex}, exclusive. If {@code fromIndex == toIndex},
* the range to be sorted is empty.
*
*
The {@code <} relation does not provide a total order on all float
* values: {@code -0.0f == 0.0f} is {@code true} and a {@code Float.NaN}
* value compares neither less than, greater than, nor equal to any value,
* even itself. This method uses the total order imposed by the method
* {@link Float#compareTo}: {@code -0.0f} is treated as less than value
* {@code 0.0f} and {@code Float.NaN} is considered greater than any
* other value and all {@code Float.NaN} values are considered equal.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
* @param fromIndex the index of the first element, inclusive, to be sorted
* @param toIndex the index of the last element, exclusive, to be sorted
*
* @throws IllegalArgumentException if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0} or {@code toIndex > a.length}
*/
public static void sort(float[] a, int fromIndex, int toIndex) {
rangeCheck(a.length, fromIndex, toIndex);
DualPivotQuicksort.sort(a, fromIndex, toIndex - 1);
}
/**
* Sorts the specified array into ascending numerical order.
*
*
The {@code <} relation does not provide a total order on all double
* values: {@code -0.0d == 0.0d} is {@code true} and a {@code Double.NaN}
* value compares neither less than, greater than, nor equal to any value,
* even itself. This method uses the total order imposed by the method
* {@link Double#compareTo}: {@code -0.0d} is treated as less than value
* {@code 0.0d} and {@code Double.NaN} is considered greater than any
* other value and all {@code Double.NaN} values are considered equal.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
*/
public static void sort(double[] a) {
DualPivotQuicksort.sort(a);
}
/**
* Sorts the specified range of the array into ascending order. The range
* to be sorted extends from the index {@code fromIndex}, inclusive, to
* the index {@code toIndex}, exclusive. If {@code fromIndex == toIndex},
* the range to be sorted is empty.
*
*
The {@code <} relation does not provide a total order on all double
* values: {@code -0.0d == 0.0d} is {@code true} and a {@code Double.NaN}
* value compares neither less than, greater than, nor equal to any value,
* even itself. This method uses the total order imposed by the method
* {@link Double#compareTo}: {@code -0.0d} is treated as less than value
* {@code 0.0d} and {@code Double.NaN} is considered greater than any
* other value and all {@code Double.NaN} values are considered equal.
*
*
Implementation note: The sorting algorithm is a Dual-Pivot Quicksort
* by Vladimir Yaroslavskiy, Jon Bentley, and Joshua Bloch. This algorithm
* offers O(n log(n)) performance on many data sets that cause other
* quicksorts to degrade to quadratic performance, and is typically
* faster than traditional (one-pivot) Quicksort implementations.
*
* @param a the array to be sorted
* @param fromIndex the index of the first element, inclusive, to be sorted
* @param toIndex the index of the last element, exclusive, to be sorted
*
* @throws IllegalArgumentException if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0} or {@code toIndex > a.length}
*/
public static void sort(double[] a, int fromIndex, int toIndex) {
rangeCheck(a.length, fromIndex, toIndex);
DualPivotQuicksort.sort(a, fromIndex, toIndex - 1);
}
/*
* Sorting of complex type arrays.
*/
/**
* Old merge sort implementation can be selected (for
* compatibility with broken comparators) using a system property.
* Cannot be a static boolean in the enclosing class due to
* circular dependencies. To be removed in a future release.
*/
static final class LegacyMergeSort {
private static final boolean userRequested = false;
}
/*
* If this platform has an optimizing VM, check whether ComparableTimSort
* offers any performance benefit over TimSort in conjunction with a
* comparator that returns:
* {@code ((Comparable)first).compareTo(Second)}.
* If not, you are better off deleting ComparableTimSort to
* eliminate the code duplication. In other words, the commented
* out code below is the preferable implementation for sorting
* arrays of Comparables if it offers sufficient performance.
*/
// /**
// * A comparator that implements the natural ordering of a group of
// * mutually comparable elements. Using this comparator saves us
// * from duplicating most of the code in this file (one version for
// * Comparables, one for explicit Comparators).
// */
// private static final Comparator NATURAL_ORDER =
// new Comparator() {
// @SuppressWarnings("unchecked")
// public int compare(Object first, Object second) {
// return ((Comparable)first).compareTo(second);
// }
// };
//
// public static void sort(Object[] a) {
// sort(a, 0, a.length, NATURAL_ORDER);
// }
//
// public static void sort(Object[] a, int fromIndex, int toIndex) {
// sort(a, fromIndex, toIndex, NATURAL_ORDER);
// }
/**
* Sorts the specified array of objects into ascending order, according
* to the {@linkplain Comparable natural ordering} of its elements.
* All elements in the array must implement the {@link Comparable}
* interface. Furthermore, all elements in the array must be
* mutually comparable (that is, {@code e1.compareTo(e2)} must
* not throw a {@code ClassCastException} for any elements {@code e1}
* and {@code e2} in the array).
*
* This sort is guaranteed to be stable : equal elements will
* not be reordered as a result of the sort.
*
*
Implementation note: This implementation is a stable, adaptive,
* iterative mergesort that requires far fewer than n lg(n) comparisons
* when the input array is partially sorted, while offering the
* performance of a traditional mergesort when the input array is
* randomly ordered. If the input array is nearly sorted, the
* implementation requires approximately n comparisons. Temporary
* storage requirements vary from a small constant for nearly sorted
* input arrays to n/2 object references for randomly ordered input
* arrays.
*
*
The implementation takes equal advantage of ascending and
* descending order in its input array, and can take advantage of
* ascending and descending order in different parts of the the same
* input array. It is well-suited to merging two or more sorted arrays:
* simply concatenate the arrays and sort the resulting array.
*
*
The implementation was adapted from Tim Peters's list sort for Python
* (
* TimSort ). It uses techiques from Peter McIlroy's "Optimistic
* Sorting and Information Theoretic Complexity", in Proceedings of the
* Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474,
* January 1993.
*
* @param a the array to be sorted
* @throws ClassCastException if the array contains elements that are not
* mutually comparable (for example, strings and integers)
* @throws IllegalArgumentException (optional) if the natural
* ordering of the array elements is found to violate the
* {@link Comparable} contract
*/
public static void sort(Object[] a) {
if (LegacyMergeSort.userRequested)
legacyMergeSort(a);
else
ComparableTimSort.sort(a);
}
/** To be removed in a future release. */
private static void legacyMergeSort(Object[] a) {
Object[] aux = a.clone();
mergeSort(aux, a, 0, a.length, 0);
}
/**
* Sorts the specified range of the specified array of objects into
* ascending order, according to the
* {@linkplain Comparable natural ordering} of its
* elements. The range to be sorted extends from index
* {@code fromIndex}, inclusive, to index {@code toIndex}, exclusive.
* (If {@code fromIndex==toIndex}, the range to be sorted is empty.) All
* elements in this range must implement the {@link Comparable}
* interface. Furthermore, all elements in this range must be mutually
* comparable (that is, {@code e1.compareTo(e2)} must not throw a
* {@code ClassCastException} for any elements {@code e1} and
* {@code e2} in the array).
*
*
This sort is guaranteed to be stable : equal elements will
* not be reordered as a result of the sort.
*
*
Implementation note: This implementation is a stable, adaptive,
* iterative mergesort that requires far fewer than n lg(n) comparisons
* when the input array is partially sorted, while offering the
* performance of a traditional mergesort when the input array is
* randomly ordered. If the input array is nearly sorted, the
* implementation requires approximately n comparisons. Temporary
* storage requirements vary from a small constant for nearly sorted
* input arrays to n/2 object references for randomly ordered input
* arrays.
*
*
The implementation takes equal advantage of ascending and
* descending order in its input array, and can take advantage of
* ascending and descending order in different parts of the the same
* input array. It is well-suited to merging two or more sorted arrays:
* simply concatenate the arrays and sort the resulting array.
*
*
The implementation was adapted from Tim Peters's list sort for Python
* (
* TimSort ). It uses techiques from Peter McIlroy's "Optimistic
* Sorting and Information Theoretic Complexity", in Proceedings of the
* Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474,
* January 1993.
*
* @param a the array to be sorted
* @param fromIndex the index of the first element (inclusive) to be
* sorted
* @param toIndex the index of the last element (exclusive) to be sorted
* @throws IllegalArgumentException if {@code fromIndex > toIndex} or
* (optional) if the natural ordering of the array elements is
* found to violate the {@link Comparable} contract
* @throws ArrayIndexOutOfBoundsException if {@code fromIndex < 0} or
* {@code toIndex > a.length}
* @throws ClassCastException if the array contains elements that are
* not mutually comparable (for example, strings and
* integers).
*/
public static void sort(Object[] a, int fromIndex, int toIndex) {
if (LegacyMergeSort.userRequested)
legacyMergeSort(a, fromIndex, toIndex);
else
ComparableTimSort.sort(a, fromIndex, toIndex);
}
/** To be removed in a future release. */
private static void legacyMergeSort(Object[] a,
int fromIndex, int toIndex) {
rangeCheck(a.length, fromIndex, toIndex);
Object[] aux = copyOfRange(a, fromIndex, toIndex);
mergeSort(aux, a, fromIndex, toIndex, -fromIndex);
}
/**
* Tuning parameter: list size at or below which insertion sort will be
* used in preference to mergesort.
* To be removed in a future release.
*/
private static final int INSERTIONSORT_THRESHOLD = 7;
/**
* Src is the source array that starts at index 0
* Dest is the (possibly larger) array destination with a possible offset
* low is the index in dest to start sorting
* high is the end index in dest to end sorting
* off is the offset to generate corresponding low, high in src
* To be removed in a future release.
*/
private static void mergeSort(Object[] src,
Object[] dest,
int low,
int high,
int off) {
int length = high - low;
// Insertion sort on smallest arrays
if (length < INSERTIONSORT_THRESHOLD) {
for (int i=low; ilow &&
((Comparable) dest[j-1]).compareTo(dest[j])>0; j--)
swap(dest, j, j-1);
return;
}
// Recursively sort halves of dest into src
int destLow = low;
int destHigh = high;
low += off;
high += off;
int mid = (low + high) >>> 1;
mergeSort(dest, src, low, mid, -off);
mergeSort(dest, src, mid, high, -off);
// If list is already sorted, just copy from src to dest. This is an
// optimization that results in faster sorts for nearly ordered lists.
if (((Comparable)src[mid-1]).compareTo(src[mid]) <= 0) {
System.arraycopy(src, low, dest, destLow, length);
return;
}
// Merge sorted halves (now in src) into dest
for(int i = destLow, p = low, q = mid; i < destHigh; i++) {
if (q >= high || p < mid && ((Comparable)src[p]).compareTo(src[q])<=0)
dest[i] = src[p++];
else
dest[i] = src[q++];
}
}
/**
* Swaps x[a] with x[b].
*/
private static void swap(Object[] x, int a, int b) {
Object t = x[a];
x[a] = x[b];
x[b] = t;
}
/**
* Sorts the specified array of objects according to the order induced by
* the specified comparator. All elements in the array must be
* mutually comparable by the specified comparator (that is,
* {@code c.compare(e1, e2)} must not throw a {@code ClassCastException}
* for any elements {@code e1} and {@code e2} in the array).
*
* This sort is guaranteed to be stable : equal elements will
* not be reordered as a result of the sort.
*
*
Implementation note: This implementation is a stable, adaptive,
* iterative mergesort that requires far fewer than n lg(n) comparisons
* when the input array is partially sorted, while offering the
* performance of a traditional mergesort when the input array is
* randomly ordered. If the input array is nearly sorted, the
* implementation requires approximately n comparisons. Temporary
* storage requirements vary from a small constant for nearly sorted
* input arrays to n/2 object references for randomly ordered input
* arrays.
*
*
The implementation takes equal advantage of ascending and
* descending order in its input array, and can take advantage of
* ascending and descending order in different parts of the the same
* input array. It is well-suited to merging two or more sorted arrays:
* simply concatenate the arrays and sort the resulting array.
*
*
The implementation was adapted from Tim Peters's list sort for Python
* (
* TimSort ). It uses techiques from Peter McIlroy's "Optimistic
* Sorting and Information Theoretic Complexity", in Proceedings of the
* Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474,
* January 1993.
*
* @param a the array to be sorted
* @param c the comparator to determine the order of the array. A
* {@code null} value indicates that the elements'
* {@linkplain Comparable natural ordering} should be used.
* @throws ClassCastException if the array contains elements that are
* not mutually comparable using the specified comparator
* @throws IllegalArgumentException (optional) if the comparator is
* found to violate the {@link Comparator} contract
*/
public static void sort(T[] a, Comparator c) {
if (LegacyMergeSort.userRequested)
legacyMergeSort(a, c);
else
TimSort.sort(a, c);
}
/** To be removed in a future release. */
private static void legacyMergeSort(T[] a, Comparator c) {
T[] aux = a.clone();
if (c==null)
mergeSort(aux, a, 0, a.length, 0);
else
mergeSort(aux, a, 0, a.length, 0, c);
}
/**
* Sorts the specified range of the specified array of objects according
* to the order induced by the specified comparator. The range to be
* sorted extends from index {@code fromIndex}, inclusive, to index
* {@code toIndex}, exclusive. (If {@code fromIndex==toIndex}, the
* range to be sorted is empty.) All elements in the range must be
* mutually comparable by the specified comparator (that is,
* {@code c.compare(e1, e2)} must not throw a {@code ClassCastException}
* for any elements {@code e1} and {@code e2} in the range).
*
* This sort is guaranteed to be stable : equal elements will
* not be reordered as a result of the sort.
*
*
Implementation note: This implementation is a stable, adaptive,
* iterative mergesort that requires far fewer than n lg(n) comparisons
* when the input array is partially sorted, while offering the
* performance of a traditional mergesort when the input array is
* randomly ordered. If the input array is nearly sorted, the
* implementation requires approximately n comparisons. Temporary
* storage requirements vary from a small constant for nearly sorted
* input arrays to n/2 object references for randomly ordered input
* arrays.
*
*
The implementation takes equal advantage of ascending and
* descending order in its input array, and can take advantage of
* ascending and descending order in different parts of the the same
* input array. It is well-suited to merging two or more sorted arrays:
* simply concatenate the arrays and sort the resulting array.
*
*
The implementation was adapted from Tim Peters's list sort for Python
* (
* TimSort ). It uses techiques from Peter McIlroy's "Optimistic
* Sorting and Information Theoretic Complexity", in Proceedings of the
* Fourth Annual ACM-SIAM Symposium on Discrete Algorithms, pp 467-474,
* January 1993.
*
* @param a the array to be sorted
* @param fromIndex the index of the first element (inclusive) to be
* sorted
* @param toIndex the index of the last element (exclusive) to be sorted
* @param c the comparator to determine the order of the array. A
* {@code null} value indicates that the elements'
* {@linkplain Comparable natural ordering} should be used.
* @throws ClassCastException if the array contains elements that are not
* mutually comparable using the specified comparator.
* @throws IllegalArgumentException if {@code fromIndex > toIndex} or
* (optional) if the comparator is found to violate the
* {@link Comparator} contract
* @throws ArrayIndexOutOfBoundsException if {@code fromIndex < 0} or
* {@code toIndex > a.length}
*/
public static void sort(T[] a, int fromIndex, int toIndex,
Comparator c) {
if (LegacyMergeSort.userRequested)
legacyMergeSort(a, fromIndex, toIndex, c);
else
TimSort.sort(a, fromIndex, toIndex, c);
}
/** To be removed in a future release. */
private static void legacyMergeSort(T[] a, int fromIndex, int toIndex,
Comparator c) {
rangeCheck(a.length, fromIndex, toIndex);
T[] aux = copyOfRange(a, fromIndex, toIndex);
if (c==null)
mergeSort(aux, a, fromIndex, toIndex, -fromIndex);
else
mergeSort(aux, a, fromIndex, toIndex, -fromIndex, c);
}
/**
* Src is the source array that starts at index 0
* Dest is the (possibly larger) array destination with a possible offset
* low is the index in dest to start sorting
* high is the end index in dest to end sorting
* off is the offset into src corresponding to low in dest
* To be removed in a future release.
*/
private static void mergeSort(Object[] src,
Object[] dest,
int low, int high, int off,
Comparator c) {
int length = high - low;
// Insertion sort on smallest arrays
if (length < INSERTIONSORT_THRESHOLD) {
for (int i=low; ilow && c.compare(dest[j-1], dest[j])>0; j--)
swap(dest, j, j-1);
return;
}
// Recursively sort halves of dest into src
int destLow = low;
int destHigh = high;
low += off;
high += off;
int mid = (low + high) >>> 1;
mergeSort(dest, src, low, mid, -off, c);
mergeSort(dest, src, mid, high, -off, c);
// If list is already sorted, just copy from src to dest. This is an
// optimization that results in faster sorts for nearly ordered lists.
if (c.compare(src[mid-1], src[mid]) <= 0) {
System.arraycopy(src, low, dest, destLow, length);
return;
}
// Merge sorted halves (now in src) into dest
for(int i = destLow, p = low, q = mid; i < destHigh; i++) {
if (q >= high || p < mid && c.compare(src[p], src[q]) <= 0)
dest[i] = src[p++];
else
dest[i] = src[q++];
}
}
/**
* Checks that {@code fromIndex} and {@code toIndex} are in
* the range and throws an appropriate exception, if they aren't.
*/
private static void rangeCheck(int length, int fromIndex, int toIndex) {
if (fromIndex > toIndex) {
throw new IllegalArgumentException(
"fromIndex(" + fromIndex + ") > toIndex(" + toIndex + ")");
}
if (fromIndex < 0) {
throw new ArrayIndexOutOfBoundsException(fromIndex);
}
if (toIndex > length) {
throw new ArrayIndexOutOfBoundsException(toIndex);
}
}
// Searching
/**
* Searches the specified array of longs for the specified value using the
* binary search algorithm. The array must be sorted (as
* by the {@link #sort(long[])} method) prior to making this call. If it
* is not sorted, the results are undefined. If the array contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element greater than the key, or a.length if all
* elements in the array are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
*/
public static int binarySearch(long[] a, long key) {
return binarySearch0(a, 0, a.length, key);
}
/**
* Searches a range of
* the specified array of longs for the specified value using the
* binary search algorithm.
* The range must be sorted (as
* by the {@link #sort(long[], int, int)} method)
* prior to making this call. If it
* is not sorted, the results are undefined. If the range contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param fromIndex the index of the first element (inclusive) to be
* searched
* @param toIndex the index of the last element (exclusive) to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array
* within the specified range;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element in the range greater than the key,
* or toIndex if all
* elements in the range are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws IllegalArgumentException
* if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0 or toIndex > a.length}
* @since 1.6
*/
public static int binarySearch(long[] a, int fromIndex, int toIndex,
long key) {
rangeCheck(a.length, fromIndex, toIndex);
return binarySearch0(a, fromIndex, toIndex, key);
}
// Like public version, but without range checks.
private static int binarySearch0(long[] a, int fromIndex, int toIndex,
long key) {
int low = fromIndex;
int high = toIndex - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
long midVal = a[mid];
if (midVal < key)
low = mid + 1;
else if (midVal > key)
high = mid - 1;
else
return mid; // key found
}
return -(low + 1); // key not found.
}
/**
* Searches the specified array of ints for the specified value using the
* binary search algorithm. The array must be sorted (as
* by the {@link #sort(int[])} method) prior to making this call. If it
* is not sorted, the results are undefined. If the array contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element greater than the key, or a.length if all
* elements in the array are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
*/
public static int binarySearch(int[] a, int key) {
return binarySearch0(a, 0, a.length, key);
}
/**
* Searches a range of
* the specified array of ints for the specified value using the
* binary search algorithm.
* The range must be sorted (as
* by the {@link #sort(int[], int, int)} method)
* prior to making this call. If it
* is not sorted, the results are undefined. If the range contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param fromIndex the index of the first element (inclusive) to be
* searched
* @param toIndex the index of the last element (exclusive) to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array
* within the specified range;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element in the range greater than the key,
* or toIndex if all
* elements in the range are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws IllegalArgumentException
* if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0 or toIndex > a.length}
* @since 1.6
*/
public static int binarySearch(int[] a, int fromIndex, int toIndex,
int key) {
rangeCheck(a.length, fromIndex, toIndex);
return binarySearch0(a, fromIndex, toIndex, key);
}
// Like public version, but without range checks.
private static int binarySearch0(int[] a, int fromIndex, int toIndex,
int key) {
int low = fromIndex;
int high = toIndex - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
int midVal = a[mid];
if (midVal < key)
low = mid + 1;
else if (midVal > key)
high = mid - 1;
else
return mid; // key found
}
return -(low + 1); // key not found.
}
/**
* Searches the specified array of shorts for the specified value using
* the binary search algorithm. The array must be sorted
* (as by the {@link #sort(short[])} method) prior to making this call. If
* it is not sorted, the results are undefined. If the array contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element greater than the key, or a.length if all
* elements in the array are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
*/
public static int binarySearch(short[] a, short key) {
return binarySearch0(a, 0, a.length, key);
}
/**
* Searches a range of
* the specified array of shorts for the specified value using
* the binary search algorithm.
* The range must be sorted
* (as by the {@link #sort(short[], int, int)} method)
* prior to making this call. If
* it is not sorted, the results are undefined. If the range contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param fromIndex the index of the first element (inclusive) to be
* searched
* @param toIndex the index of the last element (exclusive) to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array
* within the specified range;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element in the range greater than the key,
* or toIndex if all
* elements in the range are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws IllegalArgumentException
* if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0 or toIndex > a.length}
* @since 1.6
*/
public static int binarySearch(short[] a, int fromIndex, int toIndex,
short key) {
rangeCheck(a.length, fromIndex, toIndex);
return binarySearch0(a, fromIndex, toIndex, key);
}
// Like public version, but without range checks.
private static int binarySearch0(short[] a, int fromIndex, int toIndex,
short key) {
int low = fromIndex;
int high = toIndex - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
short midVal = a[mid];
if (midVal < key)
low = mid + 1;
else if (midVal > key)
high = mid - 1;
else
return mid; // key found
}
return -(low + 1); // key not found.
}
/**
* Searches the specified array of chars for the specified value using the
* binary search algorithm. The array must be sorted (as
* by the {@link #sort(char[])} method) prior to making this call. If it
* is not sorted, the results are undefined. If the array contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element greater than the key, or a.length if all
* elements in the array are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
*/
public static int binarySearch(char[] a, char key) {
return binarySearch0(a, 0, a.length, key);
}
/**
* Searches a range of
* the specified array of chars for the specified value using the
* binary search algorithm.
* The range must be sorted (as
* by the {@link #sort(char[], int, int)} method)
* prior to making this call. If it
* is not sorted, the results are undefined. If the range contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param fromIndex the index of the first element (inclusive) to be
* searched
* @param toIndex the index of the last element (exclusive) to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array
* within the specified range;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element in the range greater than the key,
* or toIndex if all
* elements in the range are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws IllegalArgumentException
* if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0 or toIndex > a.length}
* @since 1.6
*/
public static int binarySearch(char[] a, int fromIndex, int toIndex,
char key) {
rangeCheck(a.length, fromIndex, toIndex);
return binarySearch0(a, fromIndex, toIndex, key);
}
// Like public version, but without range checks.
private static int binarySearch0(char[] a, int fromIndex, int toIndex,
char key) {
int low = fromIndex;
int high = toIndex - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
char midVal = a[mid];
if (midVal < key)
low = mid + 1;
else if (midVal > key)
high = mid - 1;
else
return mid; // key found
}
return -(low + 1); // key not found.
}
/**
* Searches the specified array of bytes for the specified value using the
* binary search algorithm. The array must be sorted (as
* by the {@link #sort(byte[])} method) prior to making this call. If it
* is not sorted, the results are undefined. If the array contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element greater than the key, or a.length if all
* elements in the array are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
*/
public static int binarySearch(byte[] a, byte key) {
return binarySearch0(a, 0, a.length, key);
}
/**
* Searches a range of
* the specified array of bytes for the specified value using the
* binary search algorithm.
* The range must be sorted (as
* by the {@link #sort(byte[], int, int)} method)
* prior to making this call. If it
* is not sorted, the results are undefined. If the range contains
* multiple elements with the specified value, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param fromIndex the index of the first element (inclusive) to be
* searched
* @param toIndex the index of the last element (exclusive) to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array
* within the specified range;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element in the range greater than the key,
* or toIndex if all
* elements in the range are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws IllegalArgumentException
* if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0 or toIndex > a.length}
* @since 1.6
*/
public static int binarySearch(byte[] a, int fromIndex, int toIndex,
byte key) {
rangeCheck(a.length, fromIndex, toIndex);
return binarySearch0(a, fromIndex, toIndex, key);
}
// Like public version, but without range checks.
private static int binarySearch0(byte[] a, int fromIndex, int toIndex,
byte key) {
int low = fromIndex;
int high = toIndex - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
byte midVal = a[mid];
if (midVal < key)
low = mid + 1;
else if (midVal > key)
high = mid - 1;
else
return mid; // key found
}
return -(low + 1); // key not found.
}
/**
* Searches the specified array of doubles for the specified value using
* the binary search algorithm. The array must be sorted
* (as by the {@link #sort(double[])} method) prior to making this call.
* If it is not sorted, the results are undefined. If the array contains
* multiple elements with the specified value, there is no guarantee which
* one will be found. This method considers all NaN values to be
* equivalent and equal.
*
* @param a the array to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element greater than the key, or a.length if all
* elements in the array are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
*/
public static int binarySearch(double[] a, double key) {
return binarySearch0(a, 0, a.length, key);
}
/**
* Searches a range of
* the specified array of doubles for the specified value using
* the binary search algorithm.
* The range must be sorted
* (as by the {@link #sort(double[], int, int)} method)
* prior to making this call.
* If it is not sorted, the results are undefined. If the range contains
* multiple elements with the specified value, there is no guarantee which
* one will be found. This method considers all NaN values to be
* equivalent and equal.
*
* @param a the array to be searched
* @param fromIndex the index of the first element (inclusive) to be
* searched
* @param toIndex the index of the last element (exclusive) to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array
* within the specified range;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element in the range greater than the key,
* or toIndex if all
* elements in the range are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws IllegalArgumentException
* if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0 or toIndex > a.length}
* @since 1.6
*/
public static int binarySearch(double[] a, int fromIndex, int toIndex,
double key) {
rangeCheck(a.length, fromIndex, toIndex);
return binarySearch0(a, fromIndex, toIndex, key);
}
// Like public version, but without range checks.
private static int binarySearch0(double[] a, int fromIndex, int toIndex,
double key) {
int low = fromIndex;
int high = toIndex - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
double midVal = a[mid];
if (midVal < key)
low = mid + 1; // Neither val is NaN, thisVal is smaller
else if (midVal > key)
high = mid - 1; // Neither val is NaN, thisVal is larger
else {
long midBits = Double.doubleToLongBits(midVal);
long keyBits = Double.doubleToLongBits(key);
if (midBits == keyBits) // Values are equal
return mid; // Key found
else if (midBits < keyBits) // (-0.0, 0.0) or (!NaN, NaN)
low = mid + 1;
else // (0.0, -0.0) or (NaN, !NaN)
high = mid - 1;
}
}
return -(low + 1); // key not found.
}
/**
* Searches the specified array of floats for the specified value using
* the binary search algorithm. The array must be sorted
* (as by the {@link #sort(float[])} method) prior to making this call. If
* it is not sorted, the results are undefined. If the array contains
* multiple elements with the specified value, there is no guarantee which
* one will be found. This method considers all NaN values to be
* equivalent and equal.
*
* @param a the array to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element greater than the key, or a.length if all
* elements in the array are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
*/
public static int binarySearch(float[] a, float key) {
return binarySearch0(a, 0, a.length, key);
}
/**
* Searches a range of
* the specified array of floats for the specified value using
* the binary search algorithm.
* The range must be sorted
* (as by the {@link #sort(float[], int, int)} method)
* prior to making this call. If
* it is not sorted, the results are undefined. If the range contains
* multiple elements with the specified value, there is no guarantee which
* one will be found. This method considers all NaN values to be
* equivalent and equal.
*
* @param a the array to be searched
* @param fromIndex the index of the first element (inclusive) to be
* searched
* @param toIndex the index of the last element (exclusive) to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array
* within the specified range;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element in the range greater than the key,
* or toIndex if all
* elements in the range are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws IllegalArgumentException
* if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0 or toIndex > a.length}
* @since 1.6
*/
public static int binarySearch(float[] a, int fromIndex, int toIndex,
float key) {
rangeCheck(a.length, fromIndex, toIndex);
return binarySearch0(a, fromIndex, toIndex, key);
}
// Like public version, but without range checks.
private static int binarySearch0(float[] a, int fromIndex, int toIndex,
float key) {
int low = fromIndex;
int high = toIndex - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
float midVal = a[mid];
if (midVal < key)
low = mid + 1; // Neither val is NaN, thisVal is smaller
else if (midVal > key)
high = mid - 1; // Neither val is NaN, thisVal is larger
else {
int midBits = Float.floatToIntBits(midVal);
int keyBits = Float.floatToIntBits(key);
if (midBits == keyBits) // Values are equal
return mid; // Key found
else if (midBits < keyBits) // (-0.0, 0.0) or (!NaN, NaN)
low = mid + 1;
else // (0.0, -0.0) or (NaN, !NaN)
high = mid - 1;
}
}
return -(low + 1); // key not found.
}
/**
* Searches the specified array for the specified object using the binary
* search algorithm. The array must be sorted into ascending order
* according to the
* {@linkplain Comparable natural ordering}
* of its elements (as by the
* {@link #sort(Object[])} method) prior to making this call.
* If it is not sorted, the results are undefined.
* (If the array contains elements that are not mutually comparable (for
* example, strings and integers), it cannot be sorted according
* to the natural ordering of its elements, hence results are undefined.)
* If the array contains multiple
* elements equal to the specified object, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element greater than the key, or a.length if all
* elements in the array are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws ClassCastException if the search key is not comparable to the
* elements of the array.
*/
public static int binarySearch(Object[] a, Object key) {
return binarySearch0(a, 0, a.length, key);
}
/**
* Searches a range of
* the specified array for the specified object using the binary
* search algorithm.
* The range must be sorted into ascending order
* according to the
* {@linkplain Comparable natural ordering}
* of its elements (as by the
* {@link #sort(Object[], int, int)} method) prior to making this
* call. If it is not sorted, the results are undefined.
* (If the range contains elements that are not mutually comparable (for
* example, strings and integers), it cannot be sorted according
* to the natural ordering of its elements, hence results are undefined.)
* If the range contains multiple
* elements equal to the specified object, there is no guarantee which
* one will be found.
*
* @param a the array to be searched
* @param fromIndex the index of the first element (inclusive) to be
* searched
* @param toIndex the index of the last element (exclusive) to be searched
* @param key the value to be searched for
* @return index of the search key, if it is contained in the array
* within the specified range;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element in the range greater than the key,
* or toIndex if all
* elements in the range are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws ClassCastException if the search key is not comparable to the
* elements of the array within the specified range.
* @throws IllegalArgumentException
* if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0 or toIndex > a.length}
* @since 1.6
*/
public static int binarySearch(Object[] a, int fromIndex, int toIndex,
Object key) {
rangeCheck(a.length, fromIndex, toIndex);
return binarySearch0(a, fromIndex, toIndex, key);
}
// Like public version, but without range checks.
private static int binarySearch0(Object[] a, int fromIndex, int toIndex,
Object key) {
int low = fromIndex;
int high = toIndex - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
Comparable midVal = (Comparable)a[mid];
int cmp = midVal.compareTo(key);
if (cmp < 0)
low = mid + 1;
else if (cmp > 0)
high = mid - 1;
else
return mid; // key found
}
return -(low + 1); // key not found.
}
/**
* Searches the specified array for the specified object using the binary
* search algorithm. The array must be sorted into ascending order
* according to the specified comparator (as by the
* {@link #sort(Object[], Comparator) sort(T[], Comparator)}
* method) prior to making this call. If it is
* not sorted, the results are undefined.
* If the array contains multiple
* elements equal to the specified object, there is no guarantee which one
* will be found.
*
* @param a the array to be searched
* @param key the value to be searched for
* @param c the comparator by which the array is ordered. A
* null value indicates that the elements'
* {@linkplain Comparable natural ordering} should be used.
* @return index of the search key, if it is contained in the array;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element greater than the key, or a.length if all
* elements in the array are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws ClassCastException if the array contains elements that are not
* mutually comparable using the specified comparator,
* or the search key is not comparable to the
* elements of the array using this comparator.
*/
public static int binarySearch(T[] a, T key, Comparator c) {
return binarySearch0(a, 0, a.length, key, c);
}
/**
* Searches a range of
* the specified array for the specified object using the binary
* search algorithm.
* The range must be sorted into ascending order
* according to the specified comparator (as by the
* {@link #sort(Object[], int, int, Comparator)
* sort(T[], int, int, Comparator)}
* method) prior to making this call.
* If it is not sorted, the results are undefined.
* If the range contains multiple elements equal to the specified object,
* there is no guarantee which one will be found.
*
* @param a the array to be searched
* @param fromIndex the index of the first element (inclusive) to be
* searched
* @param toIndex the index of the last element (exclusive) to be searched
* @param key the value to be searched for
* @param c the comparator by which the array is ordered. A
* null value indicates that the elements'
* {@linkplain Comparable natural ordering} should be used.
* @return index of the search key, if it is contained in the array
* within the specified range;
* otherwise, (-(insertion point ) - 1) . The
* insertion point is defined as the point at which the
* key would be inserted into the array: the index of the first
* element in the range greater than the key,
* or toIndex if all
* elements in the range are less than the specified key. Note
* that this guarantees that the return value will be >= 0 if
* and only if the key is found.
* @throws ClassCastException if the range contains elements that are not
* mutually comparable using the specified comparator,
* or the search key is not comparable to the
* elements in the range using this comparator.
* @throws IllegalArgumentException
* if {@code fromIndex > toIndex}
* @throws ArrayIndexOutOfBoundsException
* if {@code fromIndex < 0 or toIndex > a.length}
* @since 1.6
*/
public static int binarySearch(T[] a, int fromIndex, int toIndex,
T key, Comparator c) {
rangeCheck(a.length, fromIndex, toIndex);
return binarySearch0(a, fromIndex, toIndex, key, c);
}
// Like public version, but without range checks.
private static int binarySearch0(T[] a, int fromIndex, int toIndex,
T key, Comparator c) {
if (c == null) {
return binarySearch0(a, fromIndex, toIndex, key);
}
int low = fromIndex;
int high = toIndex - 1;
while (low <= high) {
int mid = (low + high) >>> 1;
T midVal = a[mid];
int cmp = c.compare(midVal, key);
if (cmp < 0)
low = mid + 1;
else if (cmp > 0)
high = mid - 1;
else
return mid; // key found
}
return -(low + 1); // key not found.
}
// Equality Testing
/**
* Returns true if the two specified arrays of longs are
* equal to one another. Two arrays are considered equal if both
* arrays contain the same number of elements, and all corresponding pairs
* of elements in the two arrays are equal. In other words, two arrays
* are equal if they contain the same elements in the same order. Also,
* two array references are considered equal if both are null .
*
* @param a one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
*/
public static boolean equals(long[] a, long[] a2) {
if (a==a2)
return true;
if (a==null || a2==null)
return false;
int length = a.length;
if (a2.length != length)
return false;
for (int i=0; itrue if the two specified arrays of ints are
* equal to one another. Two arrays are considered equal if both
* arrays contain the same number of elements, and all corresponding pairs
* of elements in the two arrays are equal. In other words, two arrays
* are equal if they contain the same elements in the same order. Also,
* two array references are considered equal if both are null .
*
* @param a one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
*/
public static boolean equals(int[] a, int[] a2) {
if (a==a2)
return true;
if (a==null || a2==null)
return false;
int length = a.length;
if (a2.length != length)
return false;
for (int i=0; itrue if the two specified arrays of shorts are
* equal to one another. Two arrays are considered equal if both
* arrays contain the same number of elements, and all corresponding pairs
* of elements in the two arrays are equal. In other words, two arrays
* are equal if they contain the same elements in the same order. Also,
* two array references are considered equal if both are null .
*
* @param a one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
*/
public static boolean equals(short[] a, short a2[]) {
if (a==a2)
return true;
if (a==null || a2==null)
return false;
int length = a.length;
if (a2.length != length)
return false;
for (int i=0; itrue if the two specified arrays of chars are
* equal to one another. Two arrays are considered equal if both
* arrays contain the same number of elements, and all corresponding pairs
* of elements in the two arrays are equal. In other words, two arrays
* are equal if they contain the same elements in the same order. Also,
* two array references are considered equal if both are null .
*
* @param a one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
*/
public static boolean equals(char[] a, char[] a2) {
if (a==a2)
return true;
if (a==null || a2==null)
return false;
int length = a.length;
if (a2.length != length)
return false;
for (int i=0; itrue if the two specified arrays of bytes are
* equal to one another. Two arrays are considered equal if both
* arrays contain the same number of elements, and all corresponding pairs
* of elements in the two arrays are equal. In other words, two arrays
* are equal if they contain the same elements in the same order. Also,
* two array references are considered equal if both are null .
*
* @param a one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
*/
public static boolean equals(byte[] a, byte[] a2) {
if (a==a2)
return true;
if (a==null || a2==null)
return false;
int length = a.length;
if (a2.length != length)
return false;
for (int i=0; itrue if the two specified arrays of booleans are
* equal to one another. Two arrays are considered equal if both
* arrays contain the same number of elements, and all corresponding pairs
* of elements in the two arrays are equal. In other words, two arrays
* are equal if they contain the same elements in the same order. Also,
* two array references are considered equal if both are null .
*
* @param a one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
*/
public static boolean equals(boolean[] a, boolean[] a2) {
if (a==a2)
return true;
if (a==null || a2==null)
return false;
int length = a.length;
if (a2.length != length)
return false;
for (int i=0; itrue if the two specified arrays of doubles are
* equal to one another. Two arrays are considered equal if both
* arrays contain the same number of elements, and all corresponding pairs
* of elements in the two arrays are equal. In other words, two arrays
* are equal if they contain the same elements in the same order. Also,
* two array references are considered equal if both are null .
*
* Two doubles d1 and d2 are considered equal if:
*
new Double(d1).equals(new Double(d2))
* (Unlike the == operator, this method considers
* NaN equals to itself, and 0.0d unequal to -0.0d.)
*
* @param a one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
* @see Double#equals(Object)
*/
public static boolean equals(double[] a, double[] a2) {
if (a==a2)
return true;
if (a==null || a2==null)
return false;
int length = a.length;
if (a2.length != length)
return false;
for (int i=0; itrue if the two specified arrays of floats are
* equal to one another. Two arrays are considered equal if both
* arrays contain the same number of elements, and all corresponding pairs
* of elements in the two arrays are equal. In other words, two arrays
* are equal if they contain the same elements in the same order. Also,
* two array references are considered equal if both are null .
*
* Two floats f1 and f2 are considered equal if:
*
new Float(f1).equals(new Float(f2))
* (Unlike the == operator, this method considers
* NaN equals to itself, and 0.0f unequal to -0.0f.)
*
* @param a one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
* @see Float#equals(Object)
*/
public static boolean equals(float[] a, float[] a2) {
if (a==a2)
return true;
if (a==null || a2==null)
return false;
int length = a.length;
if (a2.length != length)
return false;
for (int i=0; itrue if the two specified arrays of Objects are
* equal to one another. The two arrays are considered equal if
* both arrays contain the same number of elements, and all corresponding
* pairs of elements in the two arrays are equal. Two objects e1
* and e2 are considered equal if (e1==null ? e2==null
* : e1.equals(e2)) . In other words, the two arrays are equal if
* they contain the same elements in the same order. Also, two array
* references are considered equal if both are null .
*
* @param a one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
*/
public static boolean equals(Object[] a, Object[] a2) {
if (a==a2)
return true;
if (a==null || a2==null)
return false;
int length = a.length;
if (a2.length != length)
return false;
for (int i=0; ifromIndex, inclusive, to index
* toIndex , exclusive. (If fromIndex==toIndex , the
* range to be filled is empty.)
*
* @param a the array to be filled
* @param fromIndex the index of the first element (inclusive) to be
* filled with the specified value
* @param toIndex the index of the last element (exclusive) to be
* filled with the specified value
* @param val the value to be stored in all elements of the array
* @throws IllegalArgumentException if fromIndex > toIndex
* @throws ArrayIndexOutOfBoundsException if fromIndex < 0 or
* toIndex > a.length
*/
public static void fill(long[] a, int fromIndex, int toIndex, long val) {
rangeCheck(a.length, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++)
a[i] = val;
}
/**
* Assigns the specified int value to each element of the specified array
* of ints.
*
* @param a the array to be filled
* @param val the value to be stored in all elements of the array
*/
public static void fill(int[] a, int val) {
for (int i = 0, len = a.length; i < len; i++)
a[i] = val;
}
/**
* Assigns the specified int value to each element of the specified
* range of the specified array of ints. The range to be filled
* extends from index fromIndex , inclusive, to index
* toIndex , exclusive. (If fromIndex==toIndex , the
* range to be filled is empty.)
*
* @param a the array to be filled
* @param fromIndex the index of the first element (inclusive) to be
* filled with the specified value
* @param toIndex the index of the last element (exclusive) to be
* filled with the specified value
* @param val the value to be stored in all elements of the array
* @throws IllegalArgumentException if fromIndex > toIndex
* @throws ArrayIndexOutOfBoundsException if fromIndex < 0 or
* toIndex > a.length
*/
public static void fill(int[] a, int fromIndex, int toIndex, int val) {
rangeCheck(a.length, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++)
a[i] = val;
}
/**
* Assigns the specified short value to each element of the specified array
* of shorts.
*
* @param a the array to be filled
* @param val the value to be stored in all elements of the array
*/
public static void fill(short[] a, short val) {
for (int i = 0, len = a.length; i < len; i++)
a[i] = val;
}
/**
* Assigns the specified short value to each element of the specified
* range of the specified array of shorts. The range to be filled
* extends from index fromIndex , inclusive, to index
* toIndex , exclusive. (If fromIndex==toIndex , the
* range to be filled is empty.)
*
* @param a the array to be filled
* @param fromIndex the index of the first element (inclusive) to be
* filled with the specified value
* @param toIndex the index of the last element (exclusive) to be
* filled with the specified value
* @param val the value to be stored in all elements of the array
* @throws IllegalArgumentException if fromIndex > toIndex
* @throws ArrayIndexOutOfBoundsException if fromIndex < 0 or
* toIndex > a.length
*/
public static void fill(short[] a, int fromIndex, int toIndex, short val) {
rangeCheck(a.length, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++)
a[i] = val;
}
/**
* Assigns the specified char value to each element of the specified array
* of chars.
*
* @param a the array to be filled
* @param val the value to be stored in all elements of the array
*/
public static void fill(char[] a, char val) {
for (int i = 0, len = a.length; i < len; i++)
a[i] = val;
}
/**
* Assigns the specified char value to each element of the specified
* range of the specified array of chars. The range to be filled
* extends from index fromIndex , inclusive, to index
* toIndex , exclusive. (If fromIndex==toIndex , the
* range to be filled is empty.)
*
* @param a the array to be filled
* @param fromIndex the index of the first element (inclusive) to be
* filled with the specified value
* @param toIndex the index of the last element (exclusive) to be
* filled with the specified value
* @param val the value to be stored in all elements of the array
* @throws IllegalArgumentException if fromIndex > toIndex
* @throws ArrayIndexOutOfBoundsException if fromIndex < 0 or
* toIndex > a.length
*/
public static void fill(char[] a, int fromIndex, int toIndex, char val) {
rangeCheck(a.length, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++)
a[i] = val;
}
/**
* Assigns the specified byte value to each element of the specified array
* of bytes.
*
* @param a the array to be filled
* @param val the value to be stored in all elements of the array
*/
public static void fill(byte[] a, byte val) {
for (int i = 0, len = a.length; i < len; i++)
a[i] = val;
}
/**
* Assigns the specified byte value to each element of the specified
* range of the specified array of bytes. The range to be filled
* extends from index fromIndex , inclusive, to index
* toIndex , exclusive. (If fromIndex==toIndex , the
* range to be filled is empty.)
*
* @param a the array to be filled
* @param fromIndex the index of the first element (inclusive) to be
* filled with the specified value
* @param toIndex the index of the last element (exclusive) to be
* filled with the specified value
* @param val the value to be stored in all elements of the array
* @throws IllegalArgumentException if fromIndex > toIndex
* @throws ArrayIndexOutOfBoundsException if fromIndex < 0 or
* toIndex > a.length
*/
public static void fill(byte[] a, int fromIndex, int toIndex, byte val) {
rangeCheck(a.length, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++)
a[i] = val;
}
/**
* Assigns the specified boolean value to each element of the specified
* array of booleans.
*
* @param a the array to be filled
* @param val the value to be stored in all elements of the array
*/
public static void fill(boolean[] a, boolean val) {
for (int i = 0, len = a.length; i < len; i++)
a[i] = val;
}
/**
* Assigns the specified boolean value to each element of the specified
* range of the specified array of booleans. The range to be filled
* extends from index fromIndex , inclusive, to index
* toIndex , exclusive. (If fromIndex==toIndex , the
* range to be filled is empty.)
*
* @param a the array to be filled
* @param fromIndex the index of the first element (inclusive) to be
* filled with the specified value
* @param toIndex the index of the last element (exclusive) to be
* filled with the specified value
* @param val the value to be stored in all elements of the array
* @throws IllegalArgumentException if fromIndex > toIndex
* @throws ArrayIndexOutOfBoundsException if fromIndex < 0 or
* toIndex > a.length
*/
public static void fill(boolean[] a, int fromIndex, int toIndex,
boolean val) {
rangeCheck(a.length, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++)
a[i] = val;
}
/**
* Assigns the specified double value to each element of the specified
* array of doubles.
*
* @param a the array to be filled
* @param val the value to be stored in all elements of the array
*/
public static void fill(double[] a, double val) {
for (int i = 0, len = a.length; i < len; i++)
a[i] = val;
}
/**
* Assigns the specified double value to each element of the specified
* range of the specified array of doubles. The range to be filled
* extends from index fromIndex , inclusive, to index
* toIndex , exclusive. (If fromIndex==toIndex , the
* range to be filled is empty.)
*
* @param a the array to be filled
* @param fromIndex the index of the first element (inclusive) to be
* filled with the specified value
* @param toIndex the index of the last element (exclusive) to be
* filled with the specified value
* @param val the value to be stored in all elements of the array
* @throws IllegalArgumentException if fromIndex > toIndex
* @throws ArrayIndexOutOfBoundsException if fromIndex < 0 or
* toIndex > a.length
*/
public static void fill(double[] a, int fromIndex, int toIndex,double val){
rangeCheck(a.length, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++)
a[i] = val;
}
/**
* Assigns the specified float value to each element of the specified array
* of floats.
*
* @param a the array to be filled
* @param val the value to be stored in all elements of the array
*/
public static void fill(float[] a, float val) {
for (int i = 0, len = a.length; i < len; i++)
a[i] = val;
}
/**
* Assigns the specified float value to each element of the specified
* range of the specified array of floats. The range to be filled
* extends from index fromIndex , inclusive, to index
* toIndex , exclusive. (If fromIndex==toIndex , the
* range to be filled is empty.)
*
* @param a the array to be filled
* @param fromIndex the index of the first element (inclusive) to be
* filled with the specified value
* @param toIndex the index of the last element (exclusive) to be
* filled with the specified value
* @param val the value to be stored in all elements of the array
* @throws IllegalArgumentException if fromIndex > toIndex
* @throws ArrayIndexOutOfBoundsException if fromIndex < 0 or
* toIndex > a.length
*/
public static void fill(float[] a, int fromIndex, int toIndex, float val) {
rangeCheck(a.length, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++)
a[i] = val;
}
/**
* Assigns the specified Object reference to each element of the specified
* array of Objects.
*
* @param a the array to be filled
* @param val the value to be stored in all elements of the array
* @throws ArrayStoreException if the specified value is not of a
* runtime type that can be stored in the specified array
*/
public static void fill(Object[] a, Object val) {
for (int i = 0, len = a.length; i < len; i++)
a[i] = val;
}
/**
* Assigns the specified Object reference to each element of the specified
* range of the specified array of Objects. The range to be filled
* extends from index fromIndex , inclusive, to index
* toIndex , exclusive. (If fromIndex==toIndex , the
* range to be filled is empty.)
*
* @param a the array to be filled
* @param fromIndex the index of the first element (inclusive) to be
* filled with the specified value
* @param toIndex the index of the last element (exclusive) to be
* filled with the specified value
* @param val the value to be stored in all elements of the array
* @throws IllegalArgumentException if fromIndex > toIndex
* @throws ArrayIndexOutOfBoundsException if fromIndex < 0 or
* toIndex > a.length
* @throws ArrayStoreException if the specified value is not of a
* runtime type that can be stored in the specified array
*/
public static void fill(Object[] a, int fromIndex, int toIndex, Object val) {
rangeCheck(a.length, fromIndex, toIndex);
for (int i = fromIndex; i < toIndex; i++)
a[i] = val;
}
// Cloning
/**
* Copies the specified array, truncating or padding with nulls (if necessary)
* so the copy has the specified length. For all indices that are
* valid in both the original array and the copy, the two arrays will
* contain identical values. For any indices that are valid in the
* copy but not the original, the copy will contain null .
* Such indices will exist if and only if the specified length
* is greater than that of the original array.
* The resulting array is of exactly the same class as the original array.
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @return a copy of the original array, truncated or padded with nulls
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @since 1.6
*/
public static T[] copyOf(T[] original, int newLength) {
return (T[]) copyOf(original, newLength, original.getClass());
}
/**
* Copies the specified array, truncating or padding with nulls (if necessary)
* so the copy has the specified length. For all indices that are
* valid in both the original array and the copy, the two arrays will
* contain identical values. For any indices that are valid in the
* copy but not the original, the copy will contain null .
* Such indices will exist if and only if the specified length
* is greater than that of the original array.
* The resulting array is of the class newType .
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @param newType the class of the copy to be returned
* @return a copy of the original array, truncated or padded with nulls
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @throws ArrayStoreException if an element copied from
* original is not of a runtime type that can be stored in
* an array of class newType
* @since 1.6
*/
public static T[] copyOf(U[] original, int newLength, Class newType) {
T[] copy = ((Object)newType == (Object)Object[].class)
? (T[]) new Object[newLength]
: (T[]) Array.newInstance(newType.getComponentType(), newLength);
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
/**
* Copies the specified array, truncating or padding with zeros (if necessary)
* so the copy has the specified length. For all indices that are
* valid in both the original array and the copy, the two arrays will
* contain identical values. For any indices that are valid in the
* copy but not the original, the copy will contain (byte)0 .
* Such indices will exist if and only if the specified length
* is greater than that of the original array.
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @return a copy of the original array, truncated or padded with zeros
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @since 1.6
*/
public static byte[] copyOf(byte[] original, int newLength) {
byte[] copy = new byte[newLength];
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
/**
* Copies the specified array, truncating or padding with zeros (if necessary)
* so the copy has the specified length. For all indices that are
* valid in both the original array and the copy, the two arrays will
* contain identical values. For any indices that are valid in the
* copy but not the original, the copy will contain (short)0 .
* Such indices will exist if and only if the specified length
* is greater than that of the original array.
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @return a copy of the original array, truncated or padded with zeros
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @since 1.6
*/
public static short[] copyOf(short[] original, int newLength) {
short[] copy = new short[newLength];
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
/**
* Copies the specified array, truncating or padding with zeros (if necessary)
* so the copy has the specified length. For all indices that are
* valid in both the original array and the copy, the two arrays will
* contain identical values. For any indices that are valid in the
* copy but not the original, the copy will contain 0 .
* Such indices will exist if and only if the specified length
* is greater than that of the original array.
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @return a copy of the original array, truncated or padded with zeros
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @since 1.6
*/
public static int[] copyOf(int[] original, int newLength) {
int[] copy = new int[newLength];
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
/**
* Copies the specified array, truncating or padding with zeros (if necessary)
* so the copy has the specified length. For all indices that are
* valid in both the original array and the copy, the two arrays will
* contain identical values. For any indices that are valid in the
* copy but not the original, the copy will contain 0L .
* Such indices will exist if and only if the specified length
* is greater than that of the original array.
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @return a copy of the original array, truncated or padded with zeros
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @since 1.6
*/
public static long[] copyOf(long[] original, int newLength) {
long[] copy = new long[newLength];
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
/**
* Copies the specified array, truncating or padding with null characters (if necessary)
* so the copy has the specified length. For all indices that are valid
* in both the original array and the copy, the two arrays will contain
* identical values. For any indices that are valid in the copy but not
* the original, the copy will contain '\\u000' . Such indices
* will exist if and only if the specified length is greater than that of
* the original array.
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @return a copy of the original array, truncated or padded with null characters
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @since 1.6
*/
public static char[] copyOf(char[] original, int newLength) {
char[] copy = new char[newLength];
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
/**
* Copies the specified array, truncating or padding with zeros (if necessary)
* so the copy has the specified length. For all indices that are
* valid in both the original array and the copy, the two arrays will
* contain identical values. For any indices that are valid in the
* copy but not the original, the copy will contain 0f .
* Such indices will exist if and only if the specified length
* is greater than that of the original array.
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @return a copy of the original array, truncated or padded with zeros
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @since 1.6
*/
public static float[] copyOf(float[] original, int newLength) {
float[] copy = new float[newLength];
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
/**
* Copies the specified array, truncating or padding with zeros (if necessary)
* so the copy has the specified length. For all indices that are
* valid in both the original array and the copy, the two arrays will
* contain identical values. For any indices that are valid in the
* copy but not the original, the copy will contain 0d .
* Such indices will exist if and only if the specified length
* is greater than that of the original array.
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @return a copy of the original array, truncated or padded with zeros
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @since 1.6
*/
public static double[] copyOf(double[] original, int newLength) {
double[] copy = new double[newLength];
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
/**
* Copies the specified array, truncating or padding with false (if necessary)
* so the copy has the specified length. For all indices that are
* valid in both the original array and the copy, the two arrays will
* contain identical values. For any indices that are valid in the
* copy but not the original, the copy will contain false .
* Such indices will exist if and only if the specified length
* is greater than that of the original array.
*
* @param original the array to be copied
* @param newLength the length of the copy to be returned
* @return a copy of the original array, truncated or padded with false elements
* to obtain the specified length
* @throws NegativeArraySizeException if newLength is negative
* @throws NullPointerException if original is null
* @since 1.6
*/
public static boolean[] copyOf(boolean[] original, int newLength) {
boolean[] copy = new boolean[newLength];
System.arraycopy(original, 0, copy, 0,
Math.min(original.length, newLength));
return copy;
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* null is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
*
* The resulting array is of exactly the same class as the original array.
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @return a new array containing the specified range from the original array,
* truncated or padded with nulls to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @since 1.6
*/
public static T[] copyOfRange(T[] original, int from, int to) {
return copyOfRange(original, from, to, (Class) original.getClass());
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* null is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
* The resulting array is of the class newType .
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @param newType the class of the copy to be returned
* @return a new array containing the specified range from the original array,
* truncated or padded with nulls to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @throws ArrayStoreException if an element copied from
* original is not of a runtime type that can be stored in
* an array of class newType .
* @since 1.6
*/
public static T[] copyOfRange(U[] original, int from, int to, Class newType) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
T[] copy = ((Object)newType == (Object)Object[].class)
? (T[]) new Object[newLength]
: (T[]) Array.newInstance(newType.getComponentType(), newLength);
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* (byte)0 is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @return a new array containing the specified range from the original array,
* truncated or padded with zeros to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @since 1.6
*/
public static byte[] copyOfRange(byte[] original, int from, int to) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
byte[] copy = new byte[newLength];
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* (short)0 is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @return a new array containing the specified range from the original array,
* truncated or padded with zeros to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @since 1.6
*/
public static short[] copyOfRange(short[] original, int from, int to) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
short[] copy = new short[newLength];
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* 0 is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @return a new array containing the specified range from the original array,
* truncated or padded with zeros to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @since 1.6
*/
public static int[] copyOfRange(int[] original, int from, int to) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
int[] copy = new int[newLength];
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* 0L is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @return a new array containing the specified range from the original array,
* truncated or padded with zeros to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @since 1.6
*/
public static long[] copyOfRange(long[] original, int from, int to) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
long[] copy = new long[newLength];
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* '\\u000' is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @return a new array containing the specified range from the original array,
* truncated or padded with null characters to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @since 1.6
*/
public static char[] copyOfRange(char[] original, int from, int to) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
char[] copy = new char[newLength];
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* 0f is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @return a new array containing the specified range from the original array,
* truncated or padded with zeros to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @since 1.6
*/
public static float[] copyOfRange(float[] original, int from, int to) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
float[] copy = new float[newLength];
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* 0d is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @return a new array containing the specified range from the original array,
* truncated or padded with zeros to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @since 1.6
*/
public static double[] copyOfRange(double[] original, int from, int to) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
double[] copy = new double[newLength];
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}
/**
* Copies the specified range of the specified array into a new array.
* The initial index of the range (from ) must lie between zero
* and original.length , inclusive. The value at
* original[from] is placed into the initial element of the copy
* (unless from == original.length or from == to ).
* Values from subsequent elements in the original array are placed into
* subsequent elements in the copy. The final index of the range
* (to ), which must be greater than or equal to from ,
* may be greater than original.length , in which case
* false is placed in all elements of the copy whose index is
* greater than or equal to original.length - from . The length
* of the returned array will be to - from .
*
* @param original the array from which a range is to be copied
* @param from the initial index of the range to be copied, inclusive
* @param to the final index of the range to be copied, exclusive.
* (This index may lie outside the array.)
* @return a new array containing the specified range from the original array,
* truncated or padded with false elements to obtain the required length
* @throws ArrayIndexOutOfBoundsException if {@code from < 0}
* or {@code from > original.length}
* @throws IllegalArgumentException if from > to
* @throws NullPointerException if original is null
* @since 1.6
*/
public static boolean[] copyOfRange(boolean[] original, int from, int to) {
int newLength = to - from;
if (newLength < 0)
throw new IllegalArgumentException(from + " > " + to);
boolean[] copy = new boolean[newLength];
System.arraycopy(original, from, copy, 0,
Math.min(original.length - from, newLength));
return copy;
}
// Misc
/**
* Returns a fixed-size list backed by the specified array. (Changes to
* the returned list "write through" to the array.) This method acts
* as bridge between array-based and collection-based APIs, in
* combination with {@link Collection#toArray}. The returned list is
* serializable and implements {@link RandomAccess}.
*
* This method also provides a convenient way to create a fixed-size
* list initialized to contain several elements:
*
* List<String> stooges = Arrays.asList("Larry", "Moe", "Curly");
*
*
* @param a the array by which the list will be backed
* @return a list view of the specified array
*/
@SafeVarargs
public static List asList(T... a) {
return new ArrayList<>(a);
}
/**
* @serial include
*/
private static class ArrayList extends AbstractList
implements RandomAccess, java.io.Serializable
{
private static final long serialVersionUID = -2764017481108945198L;
private final E[] a;
ArrayList(E[] array) {
if (array==null)
throw new NullPointerException();
a = array;
}
public int size() {
return a.length;
}
public Object[] toArray() {
return a.clone();
}
public T[] toArray(T[] a) {
int size = size();
if (a.length < size)
return Arrays.copyOf(this.a, size,
(Class) a.getClass());
System.arraycopy(this.a, 0, a, 0, size);
if (a.length > size)
a[size] = null;
return a;
}
public E get(int index) {
return a[index];
}
public E set(int index, E element) {
E oldValue = a[index];
a[index] = element;
return oldValue;
}
public int indexOf(Object o) {
if (o==null) {
for (int i=0; ilong arrays a and b
* such that Arrays.equals(a, b) , it is also the case that
* Arrays.hashCode(a) == Arrays.hashCode(b) .
*
* The value returned by this method is the same value that would be
* obtained by invoking the {@link List#hashCode() hashCode }
* method on a {@link List} containing a sequence of {@link Long}
* instances representing the elements of a in the same order.
* If a is null , this method returns 0.
*
* @param a the array whose hash value to compute
* @return a content-based hash code for a
* @since 1.5
*/
public static int hashCode(long a[]) {
if (a == null)
return 0;
int result = 1;
for (long element : a) {
int elementHash = (int)(element ^ (element >>> 32));
result = 31 * result + elementHash;
}
return result;
}
/**
* Returns a hash code based on the contents of the specified array.
* For any two non-null int arrays a and b
* such that Arrays.equals(a, b) , it is also the case that
* Arrays.hashCode(a) == Arrays.hashCode(b) .
*
*
The value returned by this method is the same value that would be
* obtained by invoking the {@link List#hashCode() hashCode }
* method on a {@link List} containing a sequence of {@link Integer}
* instances representing the elements of a in the same order.
* If a is null , this method returns 0.
*
* @param a the array whose hash value to compute
* @return a content-based hash code for a
* @since 1.5
*/
public static int hashCode(int a[]) {
if (a == null)
return 0;
int result = 1;
for (int element : a)
result = 31 * result + element;
return result;
}
/**
* Returns a hash code based on the contents of the specified array.
* For any two short arrays a and b
* such that Arrays.equals(a, b) , it is also the case that
* Arrays.hashCode(a) == Arrays.hashCode(b) .
*
*
The value returned by this method is the same value that would be
* obtained by invoking the {@link List#hashCode() hashCode }
* method on a {@link List} containing a sequence of {@link Short}
* instances representing the elements of a in the same order.
* If a is null , this method returns 0.
*
* @param a the array whose hash value to compute
* @return a content-based hash code for a
* @since 1.5
*/
public static int hashCode(short a[]) {
if (a == null)
return 0;
int result = 1;
for (short element : a)
result = 31 * result + element;
return result;
}
/**
* Returns a hash code based on the contents of the specified array.
* For any two char arrays a and b
* such that Arrays.equals(a, b) , it is also the case that
* Arrays.hashCode(a) == Arrays.hashCode(b) .
*
*
The value returned by this method is the same value that would be
* obtained by invoking the {@link List#hashCode() hashCode }
* method on a {@link List} containing a sequence of {@link Character}
* instances representing the elements of a in the same order.
* If a is null , this method returns 0.
*
* @param a the array whose hash value to compute
* @return a content-based hash code for a
* @since 1.5
*/
public static int hashCode(char a[]) {
if (a == null)
return 0;
int result = 1;
for (char element : a)
result = 31 * result + element;
return result;
}
/**
* Returns a hash code based on the contents of the specified array.
* For any two byte arrays a and b
* such that Arrays.equals(a, b) , it is also the case that
* Arrays.hashCode(a) == Arrays.hashCode(b) .
*
*
The value returned by this method is the same value that would be
* obtained by invoking the {@link List#hashCode() hashCode }
* method on a {@link List} containing a sequence of {@link Byte}
* instances representing the elements of a in the same order.
* If a is null , this method returns 0.
*
* @param a the array whose hash value to compute
* @return a content-based hash code for a
* @since 1.5
*/
public static int hashCode(byte a[]) {
if (a == null)
return 0;
int result = 1;
for (byte element : a)
result = 31 * result + element;
return result;
}
/**
* Returns a hash code based on the contents of the specified array.
* For any two boolean arrays a and b
* such that Arrays.equals(a, b) , it is also the case that
* Arrays.hashCode(a) == Arrays.hashCode(b) .
*
*
The value returned by this method is the same value that would be
* obtained by invoking the {@link List#hashCode() hashCode }
* method on a {@link List} containing a sequence of {@link Boolean}
* instances representing the elements of a in the same order.
* If a is null , this method returns 0.
*
* @param a the array whose hash value to compute
* @return a content-based hash code for a
* @since 1.5
*/
public static int hashCode(boolean a[]) {
if (a == null)
return 0;
int result = 1;
for (boolean element : a)
result = 31 * result + (element ? 1231 : 1237);
return result;
}
/**
* Returns a hash code based on the contents of the specified array.
* For any two float arrays a and b
* such that Arrays.equals(a, b) , it is also the case that
* Arrays.hashCode(a) == Arrays.hashCode(b) .
*
*
The value returned by this method is the same value that would be
* obtained by invoking the {@link List#hashCode() hashCode }
* method on a {@link List} containing a sequence of {@link Float}
* instances representing the elements of a in the same order.
* If a is null , this method returns 0.
*
* @param a the array whose hash value to compute
* @return a content-based hash code for a
* @since 1.5
*/
public static int hashCode(float a[]) {
if (a == null)
return 0;
int result = 1;
for (float element : a)
result = 31 * result + Float.floatToIntBits(element);
return result;
}
/**
* Returns a hash code based on the contents of the specified array.
* For any two double arrays a and b
* such that Arrays.equals(a, b) , it is also the case that
* Arrays.hashCode(a) == Arrays.hashCode(b) .
*
*
The value returned by this method is the same value that would be
* obtained by invoking the {@link List#hashCode() hashCode }
* method on a {@link List} containing a sequence of {@link Double}
* instances representing the elements of a in the same order.
* If a is null , this method returns 0.
*
* @param a the array whose hash value to compute
* @return a content-based hash code for a
* @since 1.5
*/
public static int hashCode(double a[]) {
if (a == null)
return 0;
int result = 1;
for (double element : a) {
long bits = Double.doubleToLongBits(element);
result = 31 * result + (int)(bits ^ (bits >>> 32));
}
return result;
}
/**
* Returns a hash code based on the contents of the specified array. If
* the array contains other arrays as elements, the hash code is based on
* their identities rather than their contents. It is therefore
* acceptable to invoke this method on an array that contains itself as an
* element, either directly or indirectly through one or more levels of
* arrays.
*
*
For any two arrays a and b such that
* Arrays.equals(a, b) , it is also the case that
* Arrays.hashCode(a) == Arrays.hashCode(b) .
*
*
The value returned by this method is equal to the value that would
* be returned by Arrays.asList(a).hashCode() , unless a
* is null , in which case 0 is returned.
*
* @param a the array whose content-based hash code to compute
* @return a content-based hash code for a
* @see #deepHashCode(Object[])
* @since 1.5
*/
public static int hashCode(Object a[]) {
if (a == null)
return 0;
int result = 1;
for (Object element : a)
result = 31 * result + (element == null ? 0 : element.hashCode());
return result;
}
/**
* Returns a hash code based on the "deep contents" of the specified
* array. If the array contains other arrays as elements, the
* hash code is based on their contents and so on, ad infinitum.
* It is therefore unacceptable to invoke this method on an array that
* contains itself as an element, either directly or indirectly through
* one or more levels of arrays. The behavior of such an invocation is
* undefined.
*
*
For any two arrays a and b such that
* Arrays.deepEquals(a, b) , it is also the case that
* Arrays.deepHashCode(a) == Arrays.deepHashCode(b) .
*
*
The computation of the value returned by this method is similar to
* that of the value returned by {@link List#hashCode()} on a list
* containing the same elements as a in the same order, with one
* difference: If an element e of a is itself an array,
* its hash code is computed not by calling e.hashCode() , but as
* by calling the appropriate overloading of Arrays.hashCode(e)
* if e is an array of a primitive type, or as by calling
* Arrays.deepHashCode(e) recursively if e is an array
* of a reference type. If a is null , this method
* returns 0.
*
* @param a the array whose deep-content-based hash code to compute
* @return a deep-content-based hash code for a
* @see #hashCode(Object[])
* @since 1.5
*/
public static int deepHashCode(Object a[]) {
if (a == null)
return 0;
int result = 1;
for (Object element : a) {
int elementHash = 0;
if (element instanceof Object[])
elementHash = deepHashCode((Object[]) element);
else if (element instanceof byte[])
elementHash = hashCode((byte[]) element);
else if (element instanceof short[])
elementHash = hashCode((short[]) element);
else if (element instanceof int[])
elementHash = hashCode((int[]) element);
else if (element instanceof long[])
elementHash = hashCode((long[]) element);
else if (element instanceof char[])
elementHash = hashCode((char[]) element);
else if (element instanceof float[])
elementHash = hashCode((float[]) element);
else if (element instanceof double[])
elementHash = hashCode((double[]) element);
else if (element instanceof boolean[])
elementHash = hashCode((boolean[]) element);
else if (element != null)
elementHash = element.hashCode();
result = 31 * result + elementHash;
}
return result;
}
/**
* Returns true if the two specified arrays are deeply
* equal to one another. Unlike the {@link #equals(Object[],Object[])}
* method, this method is appropriate for use with nested arrays of
* arbitrary depth.
*
*
Two array references are considered deeply equal if both
* are null , or if they refer to arrays that contain the same
* number of elements and all corresponding pairs of elements in the two
* arrays are deeply equal.
*
*
Two possibly null elements e1 and e2 are
* deeply equal if any of the following conditions hold:
*
* e1 and e2 are both arrays of object reference
* types, and Arrays.deepEquals(e1, e2) would return true
* e1 and e2 are arrays of the same primitive
* type, and the appropriate overloading of
* Arrays.equals(e1, e2) would return true.
* e1 == e2
* e1.equals(e2) would return true.
*
* Note that this definition permits null elements at any depth.
*
* If either of the specified arrays contain themselves as elements
* either directly or indirectly through one or more levels of arrays,
* the behavior of this method is undefined.
*
* @param a1 one array to be tested for equality
* @param a2 the other array to be tested for equality
* @return true if the two arrays are equal
* @see #equals(Object[],Object[])
* @see Objects#deepEquals(Object, Object)
* @since 1.5
*/
public static boolean deepEquals(Object[] a1, Object[] a2) {
if (a1 == a2)
return true;
if (a1 == null || a2==null)
return false;
int length = a1.length;
if (a2.length != length)
return false;
for (int i = 0; i < length; i++) {
Object e1 = a1[i];
Object e2 = a2[i];
if (e1 == e2)
continue;
if (e1 == null)
return false;
// Figure out whether the two elements are equal
boolean eq = deepEquals0(e1, e2);
if (!eq)
return false;
}
return true;
}
static boolean deepEquals0(Object e1, Object e2) {
assert e1 != null;
boolean eq;
if (e1 instanceof Object[] && e2 instanceof Object[])
eq = deepEquals ((Object[]) e1, (Object[]) e2);
else if (e1 instanceof byte[] && e2 instanceof byte[])
eq = equals((byte[]) e1, (byte[]) e2);
else if (e1 instanceof short[] && e2 instanceof short[])
eq = equals((short[]) e1, (short[]) e2);
else if (e1 instanceof int[] && e2 instanceof int[])
eq = equals((int[]) e1, (int[]) e2);
else if (e1 instanceof long[] && e2 instanceof long[])
eq = equals((long[]) e1, (long[]) e2);
else if (e1 instanceof char[] && e2 instanceof char[])
eq = equals((char[]) e1, (char[]) e2);
else if (e1 instanceof float[] && e2 instanceof float[])
eq = equals((float[]) e1, (float[]) e2);
else if (e1 instanceof double[] && e2 instanceof double[])
eq = equals((double[]) e1, (double[]) e2);
else if (e1 instanceof boolean[] && e2 instanceof boolean[])
eq = equals((boolean[]) e1, (boolean[]) e2);
else
eq = e1.equals(e2);
return eq;
}
/**
* Returns a string representation of the contents of the specified array.
* The string representation consists of a list of the array's elements,
* enclosed in square brackets ("[]" ). Adjacent elements are
* separated by the characters ", " (a comma followed by a
* space). Elements are converted to strings as by
* String.valueOf(long) . Returns "null" if a
* is null .
*
* @param a the array whose string representation to return
* @return a string representation of a
* @since 1.5
*/
public static String toString(long[] a) {
if (a == null)
return "null";
int iMax = a.length - 1;
if (iMax == -1)
return "[]";
StringBuilder b = new StringBuilder();
b.append('[');
for (int i = 0; ; i++) {
b.append(a[i]);
if (i == iMax)
return b.append(']').toString();
b.append(", ");
}
}
/**
* Returns a string representation of the contents of the specified array.
* The string representation consists of a list of the array's elements,
* enclosed in square brackets ("[]" ). Adjacent elements are
* separated by the characters ", " (a comma followed by a
* space). Elements are converted to strings as by
* String.valueOf(int) . Returns "null" if a is
* null .
*
* @param a the array whose string representation to return
* @return a string representation of a
* @since 1.5
*/
public static String toString(int[] a) {
if (a == null)
return "null";
int iMax = a.length - 1;
if (iMax == -1)
return "[]";
StringBuilder b = new StringBuilder();
b.append('[');
for (int i = 0; ; i++) {
b.append(a[i]);
if (i == iMax)
return b.append(']').toString();
b.append(", ");
}
}
/**
* Returns a string representation of the contents of the specified array.
* The string representation consists of a list of the array's elements,
* enclosed in square brackets ("[]" ). Adjacent elements are
* separated by the characters ", " (a comma followed by a
* space). Elements are converted to strings as by
* String.valueOf(short) . Returns "null" if a
* is null .
*
* @param a the array whose string representation to return
* @return a string representation of a
* @since 1.5
*/
public static String toString(short[] a) {
if (a == null)
return "null";
int iMax = a.length - 1;
if (iMax == -1)
return "[]";
StringBuilder b = new StringBuilder();
b.append('[');
for (int i = 0; ; i++) {
b.append(a[i]);
if (i == iMax)
return b.append(']').toString();
b.append(", ");
}
}
/**
* Returns a string representation of the contents of the specified array.
* The string representation consists of a list of the array's elements,
* enclosed in square brackets ("[]" ). Adjacent elements are
* separated by the characters ", " (a comma followed by a
* space). Elements are converted to strings as by
* String.valueOf(char) . Returns "null" if a
* is null .
*
* @param a the array whose string representation to return
* @return a string representation of a
* @since 1.5
*/
public static String toString(char[] a) {
if (a == null)
return "null";
int iMax = a.length - 1;
if (iMax == -1)
return "[]";
StringBuilder b = new StringBuilder();
b.append('[');
for (int i = 0; ; i++) {
b.append(a[i]);
if (i == iMax)
return b.append(']').toString();
b.append(", ");
}
}
/**
* Returns a string representation of the contents of the specified array.
* The string representation consists of a list of the array's elements,
* enclosed in square brackets ("[]" ). Adjacent elements
* are separated by the characters ", " (a comma followed
* by a space). Elements are converted to strings as by
* String.valueOf(byte) . Returns "null" if
* a is null .
*
* @param a the array whose string representation to return
* @return a string representation of a
* @since 1.5
*/
public static String toString(byte[] a) {
if (a == null)
return "null";
int iMax = a.length - 1;
if (iMax == -1)
return "[]";
StringBuilder b = new StringBuilder();
b.append('[');
for (int i = 0; ; i++) {
b.append(a[i]);
if (i == iMax)
return b.append(']').toString();
b.append(", ");
}
}
/**
* Returns a string representation of the contents of the specified array.
* The string representation consists of a list of the array's elements,
* enclosed in square brackets ("[]" ). Adjacent elements are
* separated by the characters ", " (a comma followed by a
* space). Elements are converted to strings as by
* String.valueOf(boolean) . Returns "null" if
* a is null .
*
* @param a the array whose string representation to return
* @return a string representation of a
* @since 1.5
*/
public static String toString(boolean[] a) {
if (a == null)
return "null";
int iMax = a.length - 1;
if (iMax == -1)
return "[]";
StringBuilder b = new StringBuilder();
b.append('[');
for (int i = 0; ; i++) {
b.append(a[i]);
if (i == iMax)
return b.append(']').toString();
b.append(", ");
}
}
/**
* Returns a string representation of the contents of the specified array.
* The string representation consists of a list of the array's elements,
* enclosed in square brackets ("[]" ). Adjacent elements are
* separated by the characters ", " (a comma followed by a
* space). Elements are converted to strings as by
* String.valueOf(float) . Returns "null" if a
* is null .
*
* @param a the array whose string representation to return
* @return a string representation of a
* @since 1.5
*/
public static String toString(float[] a) {
if (a == null)
return "null";
int iMax = a.length - 1;
if (iMax == -1)
return "[]";
StringBuilder b = new StringBuilder();
b.append('[');
for (int i = 0; ; i++) {
b.append(a[i]);
if (i == iMax)
return b.append(']').toString();
b.append(", ");
}
}
/**
* Returns a string representation of the contents of the specified array.
* The string representation consists of a list of the array's elements,
* enclosed in square brackets ("[]" ). Adjacent elements are
* separated by the characters ", " (a comma followed by a
* space). Elements are converted to strings as by
* String.valueOf(double) . Returns "null" if a
* is null .
*
* @param a the array whose string representation to return
* @return a string representation of a
* @since 1.5
*/
public static String toString(double[] a) {
if (a == null)
return "null";
int iMax = a.length - 1;
if (iMax == -1)
return "[]";
StringBuilder b = new StringBuilder();
b.append('[');
for (int i = 0; ; i++) {
b.append(a[i]);
if (i == iMax)
return b.append(']').toString();
b.append(", ");
}
}
/**
* Returns a string representation of the contents of the specified array.
* If the array contains other arrays as elements, they are converted to
* strings by the {@link Object#toString} method inherited from
* Object , which describes their identities rather than
* their contents.
*
*
The value returned by this method is equal to the value that would
* be returned by Arrays.asList(a).toString() , unless a
* is null , in which case "null" is returned.
*
* @param a the array whose string representation to return
* @return a string representation of a
* @see #deepToString(Object[])
* @since 1.5
*/
public static String toString(Object[] a) {
if (a == null)
return "null";
int iMax = a.length - 1;
if (iMax == -1)
return "[]";
StringBuilder b = new StringBuilder();
b.append('[');
for (int i = 0; ; i++) {
b.append(String.valueOf(a[i]));
if (i == iMax)
return b.append(']').toString();
b.append(", ");
}
}
/**
* Returns a string representation of the "deep contents" of the specified
* array. If the array contains other arrays as elements, the string
* representation contains their contents and so on. This method is
* designed for converting multidimensional arrays to strings.
*
*
The string representation consists of a list of the array's
* elements, enclosed in square brackets ("[]" ). Adjacent
* elements are separated by the characters ", " (a comma
* followed by a space). Elements are converted to strings as by
* String.valueOf(Object) , unless they are themselves
* arrays.
*
*
If an element e is an array of a primitive type, it is
* converted to a string as by invoking the appropriate overloading of
* Arrays.toString(e) . If an element e is an array of a
* reference type, it is converted to a string as by invoking
* this method recursively.
*
*
To avoid infinite recursion, if the specified array contains itself
* as an element, or contains an indirect reference to itself through one
* or more levels of arrays, the self-reference is converted to the string
* "[...]" . For example, an array containing only a reference
* to itself would be rendered as "[[...]]" .
*
*
This method returns "null" if the specified array
* is null .
*
* @param a the array whose string representation to return
* @return a string representation of a
* @see #toString(Object[])
* @since 1.5
*/
public static String deepToString(Object[] a) {
if (a == null)
return "null";
int bufLen = 20 * a.length;
if (a.length != 0 && bufLen <= 0)
bufLen = Integer.MAX_VALUE;
StringBuilder buf = new StringBuilder(bufLen);
deepToString(a, buf, new HashSet());
return buf.toString();
}
private static void deepToString(Object[] a, StringBuilder buf,
Set dejaVu) {
if (a == null) {
buf.append("null");
return;
}
int iMax = a.length - 1;
if (iMax == -1) {
buf.append("[]");
return;
}
dejaVu.add(a);
buf.append('[');
for (int i = 0; ; i++) {
Object element = a[i];
if (element == null) {
buf.append("null");
} else {
Class eClass = element.getClass();
if (eClass.isArray()) {
if (eClass == byte[].class)
buf.append(toString((byte[]) element));
else if (eClass == short[].class)
buf.append(toString((short[]) element));
else if (eClass == int[].class)
buf.append(toString((int[]) element));
else if (eClass == long[].class)
buf.append(toString((long[]) element));
else if (eClass == char[].class)
buf.append(toString((char[]) element));
else if (eClass == float[].class)
buf.append(toString((float[]) element));
else if (eClass == double[].class)
buf.append(toString((double[]) element));
else if (eClass == boolean[].class)
buf.append(toString((boolean[]) element));
else { // element is an array of object references
if (dejaVu.contains(element))
buf.append("[...]");
else
deepToString((Object[])element, buf, dejaVu);
}
} else { // element is non-null and not an array
buf.append(element.toString());
}
}
if (i == iMax)
break;
buf.append(", ");
}
buf.append(']');
dejaVu.remove(a);
}
}
