Inserts the specified element at the specified position in the array. : Array Insert Remove « Collections Data Structure « Java

1. Java
2. Collections Data Structure
3. Array Insert Remove

Inserts the specified element at the specified position in the array.

      
/*   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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