/* Copyright 2004 The Apache Software Foundation
*
* Licensed 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.
*/
import java.lang.reflect.Array;
/**
* Operations on arrays, primitive arrays (like int[]) and
* primitive wrapper arrays (like Integer[]).
*
* This class tries to handle null input gracefully.
* An exception will not be thrown for a null
* array input. However, an Object array that contains a null
* element may throw an exception. Each method documents its behaviour.
*
* @author Stephen Colebourne
* @author Moritz Petersen
* @author Fredrik Westermarck
* @author Nikolay Metchev
* @author Matthew Hawthorne
* @author Tim O'Brien
* @author Pete Gieser
* @author Gary Gregory
* @author Ashwin S
* @author Maarten Coene
* @since 2.0
* @version $Id: ArrayUtils.java 632503 2008-03-01 00:21:52Z ggregory $
*/
public class Main {
/**
* Removes the first occurrence of the specified element from the
* specified array. All subsequent elements are shifted to the left
* (substracts one from their indices). If the array doesn't contains
* such an element, no elements are removed from the array.
*
* This method returns a new array with the same elements of the input
* array except the first occurrence of the specified element. The component
* type of the returned array is always the same as that of the input
* array.
*
*
* ArrayUtils.removeElement(null, 1) = null
* ArrayUtils.removeElement([], 1) = []
* ArrayUtils.removeElement([1], 2) = [1]
* ArrayUtils.removeElement([1, 3], 1) = [3]
* ArrayUtils.removeElement([1, 3, 1], 1) = [3, 1]
*
*
* @param array the array to remove the element from, may be null
* @param element the element to be removed
* @return A new array containing the existing elements except the first
* occurrence of the specified element.
* @since 2.1
*/
public static short[] removeElement(short[] array, short element) {
int index = indexOf(array, element);
if (index == -1) {
return clone(array);
}
return remove(array, index);
}
/**
* Removes the element at the specified position from the specified array.
* All subsequent elements are shifted to the left (substracts 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 null, an IndexOutOfBoundsException
* will be thrown, because in that case no valid index can be specified.
*
*
* ArrayUtils.remove([1], 0) = []
* ArrayUtils.remove([2, 6], 0) = [6]
* ArrayUtils.remove([2, 6], 1) = [2]
* ArrayUtils.remove([2, 6, 3], 1) = [2, 3]
*
*
* @param array the array to remove the element from, may not be 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 null.
* @since 2.1
*/
public static short[] remove(short[] array, int index) {
return (short[]) remove((Object) array, index);
}
/**
* Removes the element at the specified position from the specified array.
* All subsequent elements are shifted to the left (substracts 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 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 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 null.
* @since 2.1
*/
private static Object remove(Object array, int index) {
int length = getLength(array);
if (index < 0 || index >= length) {
throw new IndexOutOfBoundsException("Index: " + index + ", Length: " + length);
}
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;
}
/**
* Finds the index of the given value in the array starting at the given index.
*
* This method returns {@link #INDEX_NOT_FOUND} (-1) for a null input array.
*
* A negative startIndex is treated as zero. A startIndex larger than the array
* length will return {@link #INDEX_NOT_FOUND} (-1).
*
* @param array the array to search through for the object, may be null
* @param valueToFind the value to find
* @param startIndex the index to start searching at
* @return the index of the value within the array,
* {@link #INDEX_NOT_FOUND} (-1) if not found or null array input
*/
public static int indexOf(short[] array, short valueToFind) {
if (array == null) {
return -1;
}
for (int i = 0; i < array.length; i++) {
if (valueToFind == array[i]) {
return i;
}
}
return -1;
}
/**
* Returns the length of the specified array.
* This method can deal with Object arrays and with primitive arrays.
*
* If the input array is null, 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 0 if the array is null
* @throws IllegalArgumentException if the object arguement is not an array.
* @since 2.1
*/
public static int getLength(Object array) {
if (array == null) {
return 0;
}
return Array.getLength(array);
}
/**
* Shallow clones an array returning a typecast result and handling
* null.
*
* The objects in the array are not cloned, thus there is no special
* handling for multi-dimensional arrays.
*
* This method returns null for a null input array.
*
* @param array the array to shallow clone, may be null
* @return the cloned array, null if null input
*/
public static short[] clone(short[] array) {
if (array == null) {
return null;
}
return (short[]) array.clone();
}
}