com.github.yt.commons.util.YtArrayUtils Maven / Gradle / Ivy
package com.github.yt.commons.util;
import java.lang.reflect.Array;
/**
* copy from org.apache.commons
* @author sheng
*/
public class YtArrayUtils {
/**
* The index value when an element is not found in a list or array: {@code -1}.
* This value is returned by methods in this class and can also be used in comparisons with values returned by
* various method from {@link java.util.List}.
*/
public static final int INDEX_NOT_FOUND = -1;
/**
* Checks if an array of Objects is not empty and not {@code null}.
*
* @param the component type of the array
* @param array the array to test
* @return {@code true} if the array is not empty and not {@code null}
* @since 2.5
*/
public static boolean isNotEmpty(final T[] array) {
return !isEmpty(array);
}
/**
* Checks if an array of Objects is empty or {@code null}.
*
* @param array the array to test
* @return {@code true} if the array is empty or {@code null}
* @since 2.1
*/
public static boolean isEmpty(final Object[] array) {
return getLength(array) == 0;
}
//-----------------------------------------------------------------------
/**
*
Returns the length of the specified array.
* This method can deal with {@code Object} arrays and with primitive arrays.
*
*
If the input array is {@code null}, {@code 0} is returned.
*
*
* YtArrayUtils.getLength(null) = 0
* YtArrayUtils.getLength([]) = 0
* YtArrayUtils.getLength([null]) = 1
* YtArrayUtils.getLength([true, false]) = 2
* YtArrayUtils.getLength([1, 2, 3]) = 3
* YtArrayUtils.getLength(["a", "b", "c"]) = 3
*
*
* @param array the array to retrieve the length from, may be null
* @return The length of the array, or {@code 0} if the array is {@code null}
* @throws IllegalArgumentException if the object argument is not an array.
* @since 2.1
*/
public static int getLength(final Object array) {
if (array == null) {
return 0;
}
return Array.getLength(array);
}
/**
* Checks if the object is in the given array.
*
*
The method returns {@code false} if a {@code null} array is passed in.
*
* @param array the array to search through
* @param objectToFind the object to find
* @return {@code true} if the array contains the object
*/
public static boolean contains(final Object[] array, final Object objectToFind) {
return indexOf(array, objectToFind) != INDEX_NOT_FOUND;
}
/**
*
Finds the index of the given object in the array.
*
*
This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.
*
* @param array the array to search through for the object, may be {@code null}
* @param objectToFind the object to find, may be {@code null}
* @return the index of the object within the array,
* {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
*/
public static int indexOf(final Object[] array, final Object objectToFind) {
return indexOf(array, objectToFind, 0);
}
/**
*
Finds the index of the given object in the array starting at the given index.
*
*
This method returns {@link #INDEX_NOT_FOUND} ({@code -1}) for a {@code null} input array.
*
*
A negative startIndex is treated as zero. A startIndex larger than the array
* length will return {@link #INDEX_NOT_FOUND} ({@code -1}).
*
* @param array the array to search through for the object, may be {@code null}
* @param objectToFind the object to find, may be {@code null}
* @param startIndex the index to start searching at
* @return the index of the object within the array starting at the index,
* {@link #INDEX_NOT_FOUND} ({@code -1}) if not found or {@code null} array input
*/
public static int indexOf(final Object[] array, final Object objectToFind, int startIndex) {
if (array == null) {
return INDEX_NOT_FOUND;
}
if (startIndex < 0) {
startIndex = 0;
}
if (objectToFind == null) {
for (int i = startIndex; i < array.length; i++) {
if (array[i] == null) {
return i;
}
}
} else {
for (int i = startIndex; i < array.length; i++) {
if (objectToFind.equals(array[i])) {
return i;
}
}
}
return INDEX_NOT_FOUND;
}
}