Mega Code Archive
Inserts the specified element at the specified position in the array
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/* 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;
/**
* <p>Operations on arrays, primitive arrays (like <code>int[]</code>) and
* primitive wrapper arrays (like <code>Integer[]</code>).</p>
*
* <p>This class tries to handle <code>null</code> input gracefully.
* An exception will not be thrown for a <code>null</code>
* array input. However, an Object array that contains a <code>null</code>
* element may throw an exception. Each method documents its behaviour.</p>
*
* @author Stephen Colebourne
* @author Moritz Petersen
* @author <a href="mailto:fredrik@westermarck.com">Fredrik Westermarck</a>
* @author Nikolay Metchev
* @author Matthew Hawthorne
* @author Tim O'Brien
* @author Pete Gieser
* @author Gary Gregory
* @author <a href="mailto:equinus100@hotmail.com">Ashwin S</a>
* @author Maarten Coene
* @since 2.0
* @version $Id: ArrayUtils.java 632503 2008-03-01 00:21:52Z ggregory $
*/
public class Main {
/**
* <p>Inserts the specified element at the specified position in the array.
* Shifts the element currently at that position (if any) and any subsequent
* elements to the right (adds one to their indices).</p>
*
* <p>This method returns a new array with the same elements of the input
* array plus the given element on the specified position. The component
* type of the returned array is always the same as that of the input
* array.</p>
*
* <p>If the input array is <code>null</code>, a new one element array is returned
* whose component type is the same as the element.</p>
*
* <pre>
* ArrayUtils.add(null, 0, null) = [null]
* ArrayUtils.add(null, 0, "a") = ["a"]
* ArrayUtils.add(["a"], 1, null) = ["a", null]
* ArrayUtils.add(["a"], 1, "b") = ["a", "b"]
* ArrayUtils.add(["a", "b"], 3, "c") = ["a", "b", "c"]
* </pre>
*
* @param array the array to add the element to, may be <code>null</code>
* @param index the position of the new object
* @param element the object to add
* @return A new array containing the existing elements and the new element
* @throws IndexOutOfBoundsException if the index is out of range
* (index < 0 || index > array.length).
*/
public static Object[] add(Object[] array, int index, Object element) {
Class clss = null;
if (array != null) {
clss = array.getClass().getComponentType();
} else if (element != null) {
clss = element.getClass();
} else {
return new Object[]{null};
}
return (Object[]) add(array, index, element, clss);
}
/**
* Underlying implementation of add(array, index, element) methods.
* The last parameter is the class, which may not equal element.getClass
* for primitives.
*
* @param array the array to add the element to, may be <code>null</code>
* @param index the position of the new object
* @param element the object to add
* @param clss the type of the element being added
* @return A new array containing the existing elements and the new element
*/
private static Object add(Object array, int index, Object element, Class clss) {
if (array == null) {
if (index != 0) {
throw new IndexOutOfBoundsException("Index: " + index + ", Length: 0");
}
Object joinedArray = Array.newInstance(clss, 1);
Array.set(joinedArray, 0, element);
return joinedArray;
}
int length = Array.getLength(array);
if (index > length || index < 0) {
throw new IndexOutOfBoundsException("Index: " + index + ", Length: " + length);
}
Object result = Array.newInstance(clss, length + 1);
System.arraycopy(array, 0, result, 0, index);
Array.set(result, index, element);
if (index < length) {
System.arraycopy(array, index, result, index + 1, length - index);
}
return result;
}
}
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