interface Callback{
	void callback(int param);
}

class Client implements Callback{
	public void callback(int p){
		System.out.println("callback called with"+p);
	}
	void nonIfaceMeth(){
		System.out.println("Classes that implement interfaces "+"may also define other members,too.");
	}
}

class AnotherClient implements Callback{
	public void callback(int p){
		System.out.println("Another version of callback");
		System.out.println("p squared is "+(p*p));
	}
}

class TestIface2{
	public static void main(String args[]){
		Callback c=new Client();
		AnotherClient ob=new AnotherClient();
		c.callback(42);
		c=ob;
		c.callback(42);
	}
}