public static <T> void swap(T a, T b)
    {
        T temp = a;
        a = b;
        b = temp;
    }

     public static void main(String []args){
        Integer a = 1;
        Integer b = 2;

        swap(a, b); // Integer is object, should swap if pass by reference.

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