org.apache.logging.log4j.core.util.ArrayUtils Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache license, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the license for the specific language governing permissions and
* limitations under the license.
*/
package org.apache.logging.log4j.core.util;
import java.lang.reflect.Array;
/**
* Copied from Apache Commons Lang (including the {@code @since} tags.)
*/
public class ArrayUtils {
/**
* 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 byte[] 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.
*
*
* ArrayUtils.getLength(null) = 0
* ArrayUtils.getLength([]) = 0
* ArrayUtils.getLength([null]) = 1
* ArrayUtils.getLength([true, false]) = 2
* ArrayUtils.getLength([1, 2, 3]) = 3
* ArrayUtils.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);
}
/**
* Removes the element at the specified position from the specified array.
* All subsequent elements are shifted to the left (subtracts one from
* their indices).
*
* This method returns a new array with the same elements of the input
* array except the element on the specified position. The component
* type of the returned array is always the same as that of the input
* array.
*
* If the input array is {@code null}, an IndexOutOfBoundsException
* will be thrown, because in that case no valid index can be specified.
*
* @param array the array to remove the element from, may not be {@code null}
* @param index the position of the element to be removed
* @return A new array containing the existing elements except the element
* at the specified position.
* @throws IndexOutOfBoundsException if the index is out of range
* (index < 0 || index >= array.length), or if the array is {@code null}.
* @since 2.1
*/
private static Object remove(final Object array, final int index) {
final int length = getLength(array);
if (index < 0 || index >= length) {
throw new IndexOutOfBoundsException("Index: " + index + ", Length: " + length);
}
final Object result = Array.newInstance(array.getClass().getComponentType(), length - 1);
System.arraycopy(array, 0, result, 0, index);
if (index < length - 1) {
System.arraycopy(array, index + 1, result, index, length - index - 1);
}
return result;
}
/**
* Removes the element at the specified position from the specified array.
* All subsequent elements are shifted to the left (subtracts one from
* their indices).
*
* This method returns a new array with the same elements of the input
* array except the element on the specified position. The component
* type of the returned array is always the same as that of the input
* array.
*
* If the input array is {@code null}, an IndexOutOfBoundsException
* will be thrown, because in that case no valid index can be specified.
*
*
* ArrayUtils.remove(["a"], 0) = []
* ArrayUtils.remove(["a", "b"], 0) = ["b"]
* ArrayUtils.remove(["a", "b"], 1) = ["a"]
* ArrayUtils.remove(["a", "b", "c"], 1) = ["a", "c"]
*
*
* @param the component type of the array
* @param array the array to remove the element from, may not be {@code null}
* @param index the position of the element to be removed
* @return A new array containing the existing elements except the element
* at the specified position.
* @throws IndexOutOfBoundsException if the index is out of range
* (index < 0 || index >= array.length), or if the array is {@code null}.
* @since 2.1
*/
@SuppressWarnings("unchecked") // remove() always creates an array of the same type as its input
public static T[] remove(final T[] array, final int index) {
return (T[]) remove((Object) array, index);
}
}