Remove JPanel Components

[Haroldo Level]

Hi im triying to remove all the components ina JPanle and replace it with new ones. The JPanel is running on an applet, every time I remove all components the apllet just crashes. I also tryed revalidate and repaint and the applet still dies. here is the last code I tried:

main.removeAll();
main.add(new JLabel("Just to test"), BorderLayout.CENTER); main.revalidate();
main.repaint();

Thanks in advance for all the help you can give me xD

[Ernest Friedman-Hill]

When you say it "crashes", what do you mean, exactly? Is there a stack trace? Show it to us, and we can explain it to you.

[Haroldo Level]

The program itself still running but you can do nothing in the applet window, it just do nothing

[Ernest Friedman-Hill]

Well, you've removed all the components except a label. What do you expect it to be able to do?

[Haroldo Level]

what I mean is that it stop working. The leabel doesnt show up and it doesnt remove anithing from the window

[Ernest Friedman-Hill]

Well, generally you want to call "validate()", not "revalidate()", on a container whose contents you've changed while it's visible. Without seeing more of your code, that'd be the first thing I'd recommend.

[Haroldo Level]

I tried validate also and it didn't work, here is the complete code...

public class ChatRoom extends Applet implements ActionListener, KeyListener
{
public static final int chatPort=3737;

private JPanel main;
private JTextField input;
private JTextArea status;

public void init()
{
main=new JPanel(new BorderLayout());

main.setBorder(BorderFactory.createCompoundBorder(
BorderFactory.createLineBorder(Color.black),
BorderFactory.createEmptyBorder(5,5,5,5)));


drawConecctionRequest(main);

}

private void drawConecctionRequest(JPanel main)
{
JPanel conectionRequestNorth= new JPanel(new GridLayout(2,2));
JPanel conectionRequestCenter= new JPanel(new GridLayout(3,2));
JPanel conectionRequestSouth= new JPanel(new GridLayout(2,1));




try
{
Image im=(ImageIO.read(new File("logo.jpg"))).getScaledInstance(100, 75, Image.SCALE_AREA_AVERAGING);



JLabel nickName= new JLabel("NickName:");
JLabel empty1= new JLabel();
JLabel empty2= new JLabel();
JLabel empty3= new JLabel();
JLabel empty4= new JLabel();
JLabel empty5= new JLabel();
JLabel empty6= new JLabel();
JLabel empty7= new JLabel();
JLabel logo= new JLabel(new ImageIcon(im));

logo.setBorder(BorderFactory.createEmptyBorder(0,30,0,0));

input= new JTextField(20);
JButton connect=new JButton("Conectar");
status=new JTextArea();

status.setEditable(false);

nickName.setBorder(BorderFactory.createEmptyBorder(5,5,5,5));
input.setBorder(BorderFactory.createLineBorder(Color.BLUE));


connect.setBorder(BorderFactory.createLineBorder(Color.black));
status.setBorder(BorderFactory.createLineBorder(Color.BLUE));

connect.addActionListener(this);
input.addKeyListener(this);

conectionRequestNorth.add(nickName);
conectionRequestNorth.add(input);
conectionRequestNorth.add(empty6);

conectionRequestCenter.add(empty1);
conectionRequestCenter.add(empty2);
conectionRequestCenter.add(empty3);
conectionRequestCenter.add(connect);
conectionRequestCenter.add(empty4);
conectionRequestCenter.add(empty5);

conectionRequestSouth.add(empty7);
conectionRequestSouth.add(status);

main.add(conectionRequestSouth,BorderLayout.SOUTH);

main.add(conectionRequestNorth,BorderLayout.NORTH);
main.add(conectionRequestCenter,BorderLayout.CENTER);
main.add(logo,BorderLayout.WEST);

this.add(main,BorderLayout.CENTER);
}

catch(IOException e)
{
System.out.print(e);
}
}


public void actionPerformed(ActionEvent e)
{
if(e.getActionCommand().equals("Conectar"))
{
if(!input.getText().trim().equals(""))
{
status.setText("Conectando...");
connectToChat();
}

else
{
status.setText("Porfavor inserte su nickname.");
}
}
}

public void keyPressed(KeyEvent e)
{
if(e.getKeyCode()==10)
{
connectToChat();
}
}

public void keyTyped(KeyEvent e)
{
}

public void keyReleased(KeyEvent e)
{
}

private void connectToChat()
{
InetAddress remoteIP;
Socket ChatRoom;
BufferedReader recive;
PrintWriter send;

try
{
remoteIP=InetAddress.getLocalHost();
ChatRoom=new Socket(remoteIP,chatPort);

send= new PrintWriter( ChatRoom.getOutputStream( ), true );
recive=new BufferedReader(new InputStreamReader(ChatRoom.getInputStream()));

send.println(input.getText());

if(recive.readLine().equals("accepted"))
{
main.removeAll();
main.add(new JLabel("Just to test"), BorderLayout.CENTER);
main.revalidate();
main.repaint();
}

}

catch (UnknownHostException e)
{

}

catch(IOException e1)
{
status.setText("El Servidor esta desconectado, intente mas tarde.");
}
}


}

[Haroldo Level]

the part at that is not working is in the connectToChat Method

[Craig Wood]

You could try
1 — going back to AWT, ie, removing the "J" from your components, or

2 — changing Applet to JApplet and updating the gui with:

            if(recive.readLine().equals("accepted"))
            {
                SwingUtilities.invokeLater(new Runnable()
                {
                    public void run()
                    {
                        main.removeAll();
                        main.add(new JLabel("Just to test"), BorderLayout.CENTER); 
                        main.revalidate(); 
                        main.repaint(); 
                    }
                });
            }

Swing is fussy about multi–threading. See How to Use Threads for more information.