Question

I’m trying to make a console for a java game, in an applet. The console is an independant Frame with a TextArea, used to show loading/downloading progression.
I’m running into some problems when I try to hide the console on closing.

Here is the simplified code :

//Method inherited from the Applet class
public void init() {
    console = new Frame();
    console.setSize(500, 300);
    console.addWindowListener(new WindowAdapter(){
        public void windowClosing(WindowEvent e) {
            console.setVisible(false);
        }
    });

    consoleText = new TextArea();
    consoleText.setSize(500, 300);

    console.add(consoleText);

    console.setVisible(true);

    gameThread = new Thread() {
        public void run() {
            mainLoop();
        }
    };
    gameThread.start();
}

The thread “gameThread” simply hang when I close the Frame “console”. Even when I replace “console.setVisible(false);” with “console.setExtendedState(Frame.ICONIFIED);”, the thread still hang without any warning.
While running the applet in a browser, I have to kill the process in the task manager. Very annoying.

Using a JFrame instead does the exact same thing, except the bug is harder to reproduce.

I just want the user to be able to get rid of the console.

Does anybody have an idea ? Thanks !

Answer 1

I think that you shouldn’t be using a Frame/JFrame for this but rather a JDialog, since the window is behaving as a dialog. Also be sure that you’re using a JApplet rather than an Applet.

Edit
Note that I cannot reproduce your problem based on your displayed code snippet. Consider creating and posting an SSCCE that would show us the problem directly.

Edit 2
My SSCCE that does not reproduce your problem:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class AppletEg extends JApplet {
   private static final int MAX_LOOP = 30;
   private static final long SLEEP_TIME = 500;
   private JFrame console;
   private JTextArea consoleText;
   private Thread gameThread;

   @Override
   public void init() {
      console = new JFrame();
      console.setSize(500, 300);
      console.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
            console.setVisible(false);
         }
      });

      consoleText = new JTextArea();
      consoleText.setPreferredSize(new Dimension(500, 300));

      console.add(new JScrollPane(consoleText));

      console.setVisible(true);

      gameThread = new Thread() {
         public void run() {
            mainLoop();
         }
      };
      gameThread.start();
   }

   private void mainLoop() {
      for (int i = 0; i < MAX_LOOP; i++) {
         System.out.println("I: " + i);
         try {
            Thread.sleep(SLEEP_TIME);
         } catch (InterruptedException e) {
         }
      }
   }
}

Edit 3
My SSCCE using a JDialog:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class AppletEg extends JApplet {
   private static final int MAX_LOOP = 30;
   private static final long SLEEP_TIME = 500;
   private JDialog console;
   private JTextArea consoleText;
   private Thread gameThread;

   @Override
   public void init() {
      Window win = SwingUtilities.getWindowAncestor(this);
      console = new JDialog(win);
      consoleText = new JTextArea();
      consoleText.setPreferredSize(new Dimension(500, 300));

      console.add(new JScrollPane(consoleText));
      console.pack();
      console.setLocationByPlatform(true);
      console.setVisible(true);

      gameThread = new Thread() {
         public void run() {
            mainLoop();
         }
      };
      gameThread.start();
   }

   private void mainLoop() {
      for (int i = 0; i < MAX_LOOP; i++) {
         System.out.println("i: " + i);
         try {
            Thread.sleep(SLEEP_TIME);
         } catch (InterruptedException e) {
         }
      }
   }
}