Java Programming

Hi All,

Following code is supposed to swap integer values..
but it is not happening

  
public class Swap {
    
  public static void swap(Integer a, Integer b){
        Integer tmp = new Integer(a.intValue());
        a = b;
        b = tmp;
        System.out.println("A : "+ a +  "B : "+b);
        
    }

    public static void main(String[] args) {
        Integer a = new Integer(10);
        Integer b = new Integer(20);
        
        swap(a,b);
        
        System.out.println("A : "+ a +  "B : "+b); 
    }
}

WHY ?????

Thanks in Advance
Krishna