org.jhotdraw8.icollection.impl.ArrayHelper Maven / Gradle / Ivy
Show all versions of org.jhotdraw8.icollection Show documentation
/*
* @(#)ArrayHelper.java
* Copyright © 2022 The authors and contributors of JHotDraw. MIT License.
*/
package org.jhotdraw8.icollection.impl;
import java.lang.reflect.Array;
import java.util.Arrays;
import java.util.Objects;
import java.util.function.BiPredicate;
/**
* Provides static helper methods for arrays.
*/
public class ArrayHelper {
/**
* Don't let anyone instantiate this class.
*/
private ArrayHelper() {
}
/**
* Checks if the elements in two sub-arrays are equal to one another
* in the same order.
*
* @param a array a
* @param aFrom from-index
* @param aTo to-index
* @param b array b (can be the same as array a)
* @param bFrom from-index
* @param bTo to-index
* @return true if the two sub-arrays have the same length and
* if the elements are equal to one another in the same order
*/
public static boolean equals(T[] a, int aFrom, int aTo,
T[] b, int bFrom, int bTo) {
return equals(a, aFrom, aTo, b, bFrom, bTo, Objects::equals);
}
/**
* Checks if the elements in two sub-arrays are equal to one another
* in the same order.
*
* @param a array a
* @param aFrom from-index
* @param aTo to-index
* @param b array b (can be the same as array a)
* @param bFrom from-index
* @param bTo to-index
* @param cmp the predicate that checks if two elements are equal
* @return true if the two sub-arrays have the same length and
* if the elements are equal to one another in the same order
*/
public static boolean equals(T[] a, int aFrom, int aTo,
T[] b, int bFrom, int bTo,
BiPredicate cmp) {
Objects.checkFromToIndex(aFrom, aTo, a.length);
Objects.checkFromToIndex(bFrom, bTo, b.length);
int aLength = aTo - aFrom;
int bLength = bTo - bFrom;
if (aLength != bLength) {
return false;
}
for (int i = 0; i < aLength; i++) {
if (!cmp.test(a[aFrom++], b[bFrom++])) {
return false;
}
}
return true;
}
/**
* Copies 'src' and inserts 'value' at position 'index'.
*
* @param src an array
* @param index an index
* @param value a value
* @param the array type
* @return a new array
*/
public static T[] copyAdd(T[] src, int index, T value) {
final T[] dst = copyComponentAdd(src, index, 1);
dst[index] = value;
return dst;
}
/**
* Copies 'src' and inserts 'values' at position 'index'.
*
* @param src an array
* @param index an index
* @param values the values
* @param the array type
* @return a new array
*/
public static T[] copyAddAll(T[] src, int index, T[] values) {
final T[] dst = copyComponentAdd(src, index, values.length);
System.arraycopy(values, 0, dst, index, values.length);
return dst;
}
/**
* Copies 'src' and inserts 'numComponents' at position 'index'.
*
* The new components will have a null value.
*
* @param src an array
* @param index an index
* @param numComponents the number of array components to be added
* @param the array type
* @return a new array
*/
public static T[] copyComponentAdd(T[] src, int index, int numComponents) {
if (index == src.length) {
return Arrays.copyOf(src, src.length + numComponents);
}
@SuppressWarnings("unchecked") final T[] dst = (T[]) Array.newInstance(src.getClass().getComponentType(), src.length + numComponents);
System.arraycopy(src, 0, dst, 0, index);
System.arraycopy(src, index, dst, index + numComponents, src.length - index);
return dst;
}
/**
* Copies 'src' and removes 'numComponents' at position 'index'.
*
* @param src an array
* @param index an index
* @param numComponents the number of array components to be removed
* @param the array type
* @return a new array
*/
public static T[] copyComponentRemove(T[] src, int index, int numComponents) {
if (index == src.length - numComponents) {
return Arrays.copyOf(src, src.length - numComponents);
}
@SuppressWarnings("unchecked") final T[] dst = (T[]) Array.newInstance(src.getClass().getComponentType(), src.length - numComponents);
System.arraycopy(src, 0, dst, 0, index);
System.arraycopy(src, index + numComponents, dst, index, src.length - index - numComponents);
return dst;
}
/**
* Copies 'src' and removes one component at position 'index'.
*
* @param src an array
* @param index an index
* @param the array type
* @return a new array
*/
public static T[] copyRemove(T[] src, int index) {
return copyComponentRemove(src, index, 1);
}
/**
* Copies 'src' and sets 'value' at position 'index'.
*
* @param src an array
* @param index an index
* @param value a value
* @param the array type
* @return a new array
*/
public static T[] copySet(T[] src, int index, T value) {
final T[] dst = Arrays.copyOf(src, src.length);
dst[index] = value;
return dst;
}
}