do u mean this key word... then when ever u want to represent d current class object. just like following..

class A
    {
    int a=10;      //class parameter a
    public void abc(int a)     //passed parameter from main function a
    {
    System.out.println("a value of current class:"+this.a+"a value as an parameter"+a);
    }
    public static void main(String arg[])
    {
    abc(5);
    }
    }
    the above program gives result as .......a value of current class:10 a value as an parameter 5......
    why bcoz this.a represents class parameter and a represents passed parameter in this method.