a qn from RHE..

[vidya]

Hi..
please look at the foll code:

import java.awt.*;
import java.awt.event.*;
public class MyFrame extends Frame 
{   
    MyFrame mine ;
    public MyFrame(String title)
    {
        super(title);
        enableEvents(AWTEvent.WINDOW_EVENT_MASK);
  
     }
     public void processWindowEvent(WindowEvent we)
     {
 System.out.println("processing window event");
     }
}

The options are :
1 Adding a window listener to an instance of MyFrame will result in a compiler error .
2 Adding a window listener to an instance of MyFrame will result in throwing an error at Runtime.
3 Adding a window listener to an instance of MyFrame will result in code that compiles cleanly and executes without throwing an exception.
4 A window listener added to an instance of MYFrame will never receive notification of window events.
the answers given are C and D
D is correct,but I doubted whether option C would make the compiler ask for implementation of the rest of the methods in the interface, and modified the code like so..

import java.awt.*;
import java.awt.event.*;
public class MyFrame extends Frame 
{   
    MyFrame mine ;
    public MyFrame(String title)
    {
super(title);
enableEvents(AWTEvent.WINDOW_EVENT_MASK);
mine.addWindowListener(new WindowListener(){});
     }

     public void processWindowEvent(WindowEvent we)
     {
         System.out.println("processing window event");
     }
}

and, the compiler did scream !
isn't option D the only answer, or am I missing something?
thanks in advance,
Vidya.

[vidya]

I mean,shouldn't A and D be the answer?
Vidya.

[Jason sigel]

see this code
import java.awt.*;
import java.awt.event.*;
class MyFrame extends Frame
{ MyFrame mine ;
public MyFrame(String title) {
super(title);
enableEvents(AWTEvent.WINDOW_EVENT_MASK);
//mine.addWindowListener(new WindowListener(){});
aa1 x= new aa1();
addWindowListener(x);


}
public void processWindowEvent(WindowEvent we) { System.out.println("processing window event");
}
}
public class aa1 extends WindowAdapter{
public static void main(String args[]){
Frame frame=new MyFrame("hello");
frame.show();
}
}
AND
import java.awt.*;
import java.awt.event.*;
class MyFrame extends Frame
{ MyFrame mine ;
public MyFrame(String title) {
super(title);
enableEvents(AWTEvent.WINDOW_EVENT_MASK);
//mine.addWindowListener(new WindowListener(){});
addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{ System.exit(1);}
});

}
public void processWindowEvent(WindowEvent we) { System.out.println("processing window event");
}
}
public class aa{
public static void main(String args[]){
Frame frame=new MyFrame("hello");
frame.show();
}
}

you can add window listener class into anonymous inner class of the frame.

so
C,D are correct
jaideep

[vidya]

Oh well,yes Jaideep , you are right .
I forgot about the adapter classes..
Thanks for that

Vidya.