// program to demonstrate the difference between value semantics (primitives)
//   and reference semantics (arrays)

public class Semantics {
  public static void main(String[] args) {
    int x = 3;
    int y = 5;
    System.out.println("before swap: x = " + x + ", y = " + y);
    swap(x, y);
    System.out.println("after swap: x = " + x + ", y = " + y);
    System.out.println();
    System.out.println();  
  
    int[] nums = { 1, 2, 3, 4, 5, 6, 7, 8, 9 };
    System.out.println("before swap: nums[x] = " + nums[x] + ", nums[y] = " + nums[y]);
    swapArray(nums, x, y);
    System.out.println("after swap: nums[x] = " + nums[x] + ", nums[y] = " + nums[y]);
    System.out.println();
    System.out.println();
  }
  // swaps x and y I hope!
  public static void swap(int x, int y) {
    int temp = x;
    x = y;
    y = temp;
    System.out.println("in swap: x = " + x + ", y = " + y);
  }
  
  // swaps a[x] and a[y] I hope!
  public static void swapArray(int[] a, int x, int y) {
    int temp = a[x];
    a[x] = a[y];
    a[y] = temp;
    
    System.out.println("in swap: a[x] = " + a[x] + ", a[y] = " + a[y]);
  }
}