Unknown Source

[tactech]

Hello

Can somebody help me and tell me why I can’t change the background color of the second PN2 panel.

I get this error about unknown source

Exception in thread "AWT-EventQueue-1" java.lang.NullP ointerException
at test$myFreaking Listener.action Performed(test. java:34)
at java.awt.Button .processActionE vent(Unknown Source)
at java.awt.Button .processEvent(U nknown Source)
at java.awt.Compon ent.dispatchEve ntImpl(Unknown Source)
at java.awt.Compon ent.dispatchEve nt(Unknown Source)
at java.awt.EventQ ueue.dispatchEv ent(Unknown Source)
at java.awt.EventD ispatchThread.p umpOneEventForF ilters(Unknown Source)
at java.awt.EventD ispatchThread.p umpEventsForFil ter(Unknown Source)
at java.awt.EventD ispatchThread.p umpEventsForHie rarchy(Unknown Source)
at java.awt.EventD ispatchThread.p umpEvents(Unkno wn Source)
at java.awt.EventD ispatchThread.p umpEvents(Unkno wn Source)
at java.awt.EventD ispatchThread.r un(Unknown Source)




and this is the source

import java.applet.*;
import java.awt.*;
import java.awt.event.*;

public class  test extends Applet  {
	
	 public void init () {
		 
		    this.setSize(600,440);
		   	this.setBackground(Color.white);
		   	this.setLayout(new GridLayout(2,1));
		   	Panel PN1 = new Panel(); 
		   	this.add(PN1);
		   	
			Panel PN2 = new Panel(); 
		   	this.add(PN2);
		   	PN2.setBackground(Color.red);
		   	
		   	
		   	
		   	Button but = new Button();
		   	PN1.add(but);
		   	but.setLabel("Change Panel's Color ");
		    but.addActionListener(new myFreakingListener());
		    
		    
		    
	 }
	 class myFreakingListener  implements ActionListener{

		   public void actionPerformed(ActionEvent ae){
	    			
			  PN2.setBackground(Color.orange);
	    }
	   }	
	 Panel PN1, PN2;
}

I am doing something wrong here but I can’t find it.

Any one?

[horace1]

you have class instance variables PN1 and PN2

         Panel PN1, PN2;

but also decalre tham as local variables in init()

                        Panel PN2 = new Panel(); 
                        this.add(PN2);
                        PN2.setBackground(Color.red);

therefore in

                   public void actionPerformed(ActionEvent ae){                       
                          PN2.setBackground(Color.orange);
            }

PN2 is NULL.

code in init() should be

                        PN2 = new Panel(); 
                        this.add(PN2);
                        PN2.setBackground(Color.red);

so that the instance variable PN2 is set up to reference the new Panel()