How can i Dispose Dialog box From LWUIT Component >

Hi All,

i am Developing one mobile application using lwuit,Midlet.in that am trying to show a dialog when i press key "0". again if i press key "4" the Dialog should be closed.i leave My sample Code Here.go through and let me know the error.Dialog is showing but after i press key 4, there is know response

import com.sun.lwuit.Dialog;
import com.sun.lwuit.Dialog.*;
import com.sun.lwuit.events.ActionEvent;
import com.sun.lwuit.events.ActionListener;
import com.sun.lwuit.plaf.Border.*;
public class javaForm extends Component implements ActionListener
 {
    Dialog d;
    javaForm()
     {
       d=new Dialog(); 
     }

public void keyPressed(int key)
  {
    System.out.println("Key pressed :"+key);

      switch(key)
       {
               case 48:
                       d.show();
                       break;
               case 52:
                       d.dispose();
                       break;
               default:
                       break;
                    } 
      }
 public void actionPerformed(ActionEvent ae) 
   {
       throw new UnsupportedOperationException("Not supported yet.");
    }
 }