What's wrong with this applet?

[Arnold]

I just made my first applet. The purpose of it is to show a color map of red horizontally and blue vertically.
It compiles, but it doesn't work on a html page or a browser.
Anyone know what's wrong with it?

import java.awt.*;
import javax.swing.*;
class colors extends JApplet {
	public void init() {
		JPanel panel = new JPanel();
		panel.setLayout(new GridLayout(64, 64));
		for (short i = 0; i < 0x100; i += 4) {
			for (short j = 0; j < 0x100; j += 4) {
				JPanel subpanel = new JPanel();
				subpanel.setBackground(new Color(j, 0, i));
				panel.add(subpanel);
			}
		}
		getContentPane().add(panel);
	}
}

[Fubarable]

You may have a Swing threading issue here. What if you use SwingUtiltities.invokeAndWait to try to create the applet on the EDT (event dispatch thread) as I believe is recommended in the tutorials?

import java.awt.Color;
import java.awt.GridLayout;
import javax.swing.JApplet;
import javax.swing.JPanel;

public class Colors2 extends JApplet {
   public void init() {
      try {
         javax.swing.SwingUtilities.invokeAndWait(new Runnable() {
            public void run() {
               createGUI();
            }
         });
      }
      catch (Exception e) {
         System.err.println("createGUI didn't successfully complete");
      }
   }

   private void createGUI() {
      JPanel panel = new JPanel();
      panel.setLayout(new GridLayout(64, 64));
      for (short i = 0; i < 0x100; i += 4) {
         for (short j = 0; j < 0x100; j += 4) {
            JPanel subpanel = new JPanel();
            subpanel.setBackground(new Color(j, 0, i));
            panel.add(subpanel);
         }
      }
      
      getContentPane().add(panel);
   }
}

[Arnold]

No it still doesn't work.

Hope it's not my PC!

[Fubarable]

How does it "not work"? What specifically goes wrong?

[Arnold]

How does it "not work"? What specifically goes wrong?

The java console on my browser gives the following message, but I can't decode it:

java.lang.reflect.InvocationTargetException
	at com.sun.deploy.util.DeployAWTUtil.invokeAndWait(Unknown Source)
	at sun.plugin2.applet.Plugin2Manager.runOnEDT(Unknown Source)
	at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
	at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.RuntimeException: java.lang.IllegalAccessException: Class sun.plugin2.applet.Plugin2Manager$12 can not access a member of class colors with modifiers ""
	at sun.plugin2.applet.Plugin2Manager$12.run(Unknown Source)
	at java.awt.event.InvocationEvent.dispatch(Unknown Source)
	at java.awt.EventQueue.dispatchEvent(Unknown Source)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
	at java.awt.EventDispatchThread.run(Unknown Source)
Caused by: java.lang.IllegalAccessException: Class sun.plugin2.applet.Plugin2Manager$12 can not access a member of class colors with modifiers ""
	at sun.reflect.Reflection.ensureMemberAccess(Unknown Source)
	at java.lang.Class.newInstance0(Unknown Source)
	at java.lang.Class.newInstance(Unknown Source)
	... 9 more
Exception: java.lang.reflect.InvocationTargetException
java.lang.NullPointerException
	at sun.plugin2.applet.Plugin2Manager.findAppletJDKLevel(Unknown Source)
	at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
	at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
	at java.lang.Thread.run(Unknown Source)
Exception: java.lang.NullPointerException

When I run AppletViewer, it simply does nothing.

[Fubarable]

Are you absolutely 100% sure that this error is coming from my code above? That your HTML is requesting my class? Please double check since my changes solved this very error that I was getting with your code.

[Fubarable]

For more information on why invokeAndWait is important here, please see this tutorial:
Concurrency in Swing

On the second page, you'll find this:

In an applet, the GUI-creation task must be launched from the init method using invokeAndWait; otherwise, init may return before the GUI is created, which may cause problems for a web browser launching an applet. In any other kind of program, scheduling the GUI-creation task is usually the last thing the initial thread does, so it doesn't matter whether it uses invokeLater or invokeAndWait.

[Arnold]

Are you absolutely 100% sure that this error is coming from my code above? That your HTML is requesting my class? Please double check since my changes solved this very error that I was getting with your code.

Yes, I deleted my old java file, then renamed the new version back to colors (was colors2). I also renamed the class then recompiled.
Say, why does your code generate "colors$1.class"?

[Fubarable]

It shouldn't. It should create a Colors2$1.class instead. This is for the anonymous inner class that I create with the new Runnable().... statement.

[Arnold]

It shouldn't. It should create a Colors2$1.class instead. This is for the anonymous inner class that I create with the new Runnable().... statement.

Not familiar with inner classes.
When it was still a normal appication, it worked (not perfectly, but it did), until I converted to Applet.
I'll try to take an example Applet from my book. If that doesn't work, I'll smash my PC.