SWAPPING IN JAVA

In Java the swap function works if we use wrapped integers and pass references to them to the function. However, the Java wrapper class for int is Integer and it doesn't allow to alter the data field inside. Thus we need our own wrapper class (MyInteger below).


 // MyInteger: similar to Integer, but can change value
class MyInteger
{
 private int x;     // single data member
 public MyInteger(int xIn)
 {
                x = xIn;
 } // constructor
 public int getValue()
 {
               return x;
 }  // retrieve value
 public void insertValue(int xIn)
 {
              x = xIn;
} // insert
}

public class Swapping
{
   // swap: pass references to objects
  static void swap(MyInteger rWrap, MyInteger sWrap)
 {
      // interchange values inside objects
      int t = rWrap.getValue();
      rWrap.insertValue(sWrap.getValue());
      sWrap.insertValue(t);
   }

   public static void main(String[] args)
 {
      int a = 23, b = 47;
      System.out.println("Before. a:" + a + ", b: " + b);
      MyInteger aWrap = new MyInteger(a);
      MyInteger bWrap = new MyInteger(b);
      swap(aWrap, bWrap);
      a = aWrap.getValue();
      b = bWrap.getValue();
      System.out.println("After.  a:" + a + ", b: " + b);
   }
}