Java applet won't display in firefox

**silverglade** · 05-12-2011, 09:29 PM

Hi, I am trying to get a java applet to display in firefox and it won't run. The code is from my Java book cd. I get the following error from the browser. Any help GREATLY appreciated. Thanks. Derek:D
__________________________________________________ __________

Java Plug-in 1.6.0_25
Using JRE version 1.6.0_25-b06 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\derek
----------------------------------------------------
c: clear console window
f: finalize objects on finalization queue
g: garbage collect
h: display this help message
l: dump classloader list
m: print memory usage
o: trigger logging
q: hide console
r: reload policy configuration
s: dump system and deployment properties
t: dump thread list
v: dump thread stack
x: clear classloader cache
0-5: set trace level to <n>
----------------------------------------------------

java.lang.reflect.InvocationTargetException
at com.sun.deploy.util.DeployAWTUtil.invokeAndWait(Un known Source)
at sun.plugin2.applet.Plugin2Manager.runOnEDT(Unknown Source)
at sun.plugin2.applet.Plugin2Manager.createApplet(Unk nown Source)
at sun.plugin2.applet.Plugin2Manager$AppletExecutionR unnable.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassCastException: PushCounter cannot be cast to java.applet.Applet
at sun.plugin2.applet.Plugin2Manager$12.run(Unknown Source)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
at java.awt.EventQueue.access$000(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.awt.EventQueue$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.security.AccessControlContext$1.doIntersectio nPrivilege(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilter s(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(U nknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarch y(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)
Exception: java.lang.reflect.InvocationTargetException
__________________________________________________ ____________

Here are the contents of my html file:

Java Code:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
 
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
 
<meta name="keywords" content="" />
<meta name="description" content="" />
 
<style type="text/css">
 
</style>
</head>
<body>
 <applet code="PushCounter.class" width="100" height="100"</applet>
</body>
</html>

Here are the contents of my two .java files.

Java Code:

//********************************************************************
//  PushCounter.java       Authors: Lewis/Loftus
//
//  Demonstrates a graphical user interface and an event listener.
//********************************************************************

import javax.swing.JFrame;

public class PushCounter
{
   //-----------------------------------------------------------------
   //  Creates the main program frame.
   //-----------------------------------------------------------------
   public static void main (String[] args)
   {
      JFrame frame = new JFrame ("Push Counter");
      frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);

      frame.getContentPane().add(new PushCounterPanel());

      frame.pack();
      frame.setVisible(true);
   }
}

and here

Java Code:

//********************************************************************
//  PushCounterPanel.java       Authors: Lewis/Loftus
//
//  Demonstrates a graphical user interface and an event listener.
//********************************************************************

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

public class PushCounterPanel extends JPanel
{
   private int count;
   private JButton push;
   private JLabel label;

   //-----------------------------------------------------------------
   //  Constructor: Sets up the GUI.
   //-----------------------------------------------------------------
   public PushCounterPanel ()
   {
      count = 0;

      push = new JButton ("Push Me!");
      push.addActionListener (new ButtonListener());

      label = new JLabel ("Pushes: " + count);

      add (push);
      add (label);

      setPreferredSize (new Dimension(300, 40));
      setBackground (Color.cyan);
   }

   //*****************************************************************
   //  Represents a listener for button push (action) events.
   //*****************************************************************
   private class ButtonListener implements ActionListener
   {
      //--------------------------------------------------------------
      //  Updates the counter and label when the button is pushed.
      //--------------------------------------------------------------
      public void actionPerformed (ActionEvent event)
      {
         count++;
         label.setText("Pushes: " + count);
      }
   }
}

I have also posted this question here Java applet won't display in firefox (Beginning Java forum at JavaRanch)

**cultclassic** · 05-12-2011, 10:31 PM

Java Code:

Caused by: java.lang.ClassCastException: PushCounter cannot be cast to java.applet.Applet

means: PushCounter must extend java.applet.Applet

Tutorial on applet:
http://download.oracle.com/javase/tu...etStarted.html

**cultclassic** · 05-12-2011, 10:34 PM

also,

Java Code:

<applet code="PushCounter.class" width="100" height="100"</applet>

you have not closed the applet tag...

**silverglade** · 05-12-2011, 10:51 PM

Thank you CultClassic. I was able to not get the error now, but it only displays a light gray box in the upper left corner of browser (I didn't place it). Any more help greatly appreciated. thank you. Here is my new code fixed with the extends applet and closed applet html tag.

HTML

Java Code:

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
 
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="content-type" content="text/html; charset=utf-8" />
 
<meta name="keywords" content="" />
<meta name="description" content="" />
<link href="default.css" rel="stylesheet" type="text/css" />
<style type="text/css">
 
</style>
</head>
<body>
 <applet code="PushCounter.class" width="100" height="100"codebase="../pushcounter/"></applet>
</body>
</html>

Java file 1 (which I compile into a .class file)

Java Code:

//********************************************************************
//  PushCounter.java       Authors: Lewis/Loftus
//
//  Demonstrates a graphical user interface and an event listener.
//********************************************************************

import javax.swing.JApplet;
import javax.swing.JFrame;

public class PushCounter extends JApplet
{
   //-----------------------------------------------------------------
   //  Creates the main program frame.
   //-----------------------------------------------------------------
   public static void main (String[] args)
   {
      JFrame frame = new JFrame ("Push Counter");
      frame.setDefaultCloseOperation (JFrame.EXIT_ON_CLOSE);

      frame.getContentPane().add(new PushCounterPanel());

      frame.pack();
      frame.setVisible(true);
   }
}

Java file 2

Java Code:

//********************************************************************
//  PushCounterPanel.java       Authors: Lewis/Loftus
//
//  Demonstrates a graphical user interface and an event listener.
//********************************************************************
import javax.swing.JApplet;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class PushCounterPanel extends JPanel
{
   private int count;
   private JButton push;
   private JLabel label;

   //-----------------------------------------------------------------
   //  Constructor: Sets up the GUI.
   //-----------------------------------------------------------------
   public PushCounterPanel ()
   {
      count = 0;

      push = new JButton ("Push Me!");
      push.addActionListener (new ButtonListener());

      label = new JLabel ("Pushes: " + count);

      add (push);
      add (label);

      setPreferredSize (new Dimension(300, 40));
      setBackground (Color.cyan);
   }

   //*****************************************************************
   //  Represents a listener for button push (action) events.
   //*****************************************************************
   private class ButtonListener implements ActionListener
   {
      //--------------------------------------------------------------
      //  Updates the counter and label when the button is pushed.
      //--------------------------------------------------------------
      public void actionPerformed (ActionEvent event)
      {
         count++;
         label.setText("Pushes: " + count);
      }
   }
}