Example Program - Arrays As Parameters

public class ArrayOps
{
  public ArrayOps() { }

  // Copy source to target
  public void copy (int[] source, int[] target)
  {
    for ( int count = 0; count < source.length; count++ )
      target[ count ] = source[ count ];
  }

  /*
    list is a reference parameter. list is the same array as
    array data in the main method
  */
  public void printList (int[] list)
  {
    for ( int index = 0; index < list.length; index++ )
      System.out.print( list[index] + " ");

    System.out.println();
    System.out.println();
  }

  /*
    Array list is a local alias for array data in the main method. Any
    reference to local list is a reference to array data in function main.
  */
  public void squareList (int[] list)
  {
    for ( int index = 0; index < list.length; index++ )
      list[index] = list[index] * list[index];
  }

  /*
    This method works with a local copy of the array passed as an
    argument. Changes to local array list will have no effect on the
    array data in the calling method. This method will shift each
    value one cell to the right. The value in list[list.length-1] will be
    moved to list[0]. Before the method is completed, printList will
    be called. The point of this method is to illustrate an array as
    a value parameter.
   */
  public void rotateList (int[] list)
  {
    int temp = list[list.length-1];

    int[] listCopy = new int[ list.length ];

    copy(list, listCopy);

    for ( int loop = listCopy.length-1; loop > 0; loop-- )
      listCopy[loop] = listCopy[loop-1];
    listCopy[0] = temp;

    System.out.println("Inside of rotateList: ");
    printList (listCopy);
  }


  public static void main (String[] args)
  {
    final int MAX = 6;

    ArrayOps arrayOps = new ArrayOps();

    int[] data = new int[MAX];

    for ( int loop = 0; loop < MAX; loop++ )
      data[loop] = loop;   // initialize array

    System.out.println("Array initialized: ");

    arrayOps.printList(data); // print array in ascending order
    arrayOps.squareList (data);
    System.out.println("Array after call of squareList: ");
    arrayOps.printList (data);
    arrayOps.rotateList (data);
    System.out.println("Array after call of rotateList: ");
    arrayOps.printList (data); // print list again
  }
}