JApplet won't initialize in Web Browser...

Question

Hi,
I just started teaching myself Java a few days ago. I've got the JSE JDK, and NetBeans. I've been following the tutorials. I've been programming in C(++) and various other languages for quite a while so the programming aspect of Java has come easily. When I started delving into GUI's I started encountering problems. I'm commencing a project, and basically, I need a Java applet to run in a web browser, and people need to be able to run it in a page that they've downloaded, and stuff. You know. Anyway, so here's what I did:
In Netbeans:
New Project > General > Java Class Library
So now I have a new, empty project.
Right click Project Node > New > File/Folder...
Java GUI Forms > JApplet Form
I put it in it's own package called "hello"
Add a JLabel from the Palette onto the GUI Designer thing.
Right-Click Project Node > Build Project:
init:
deps-jar:
Created dir: D:\Adrien Pellerin\Apps\JavaLibrary5\build\classes
Compiling 1 source file to D:\Adrien Pellerin\Apps\JavaLibrary5\build\classes
compile:
Created dir: D:\Adrien Pellerin\Apps\JavaLibrary5\dist
Building jar: D:\Adrien Pellerin\Apps\JavaLibrary5\dist\JavaLibrary5.jar
jar:
BUILD SUCCESSFUL (total time: 0 seconds)Right click NewJApplet.java > Run File: It works fine.
Go to project folder > build > classes > view NewJApplet.html
It opens in IE. And it says "Loading Java Applet Failed."
Here's what it says in the console:
java.lang.NoClassDefFoundError: org/jdesktop/layout/GroupLayout$Group
     at java.lang.Class.getDeclaredConstructors0(Native Method)
     at java.lang.Class.privateGetDeclaredConstructors(Unknown Source)
     at java.lang.Class.getConstructor0(Unknown Source)
     at java.lang.Class.newInstance0(Unknown Source)
     at java.lang.Class.newInstance(Unknown Source)
     at sun.applet.AppletPanel.createApplet(Unknown Source)
     at sun.plugin.AppletViewer.createApplet(Unknown Source)
     at sun.applet.AppletPanel.runLoader(Unknown Source)
     at sun.applet.AppletPanel.run(Unknown Source)
     at java.lang.Thread.run(Unknown Source)And here's the code for the original Java file:
* NewJApplet.java
* Created on October 11, 2006, 2:38 PM
package hello;
* @author  Adrien Pellerin
public class NewJApplet extends javax.swing.JApplet {
    /** Initializes the applet NewJApplet */
    public void init() {
        try {
            java.awt.EventQueue.invokeAndWait(new Runnable() {
                public void run() {
                    initComponents();
        } catch (Exception ex) {
            ex.printStackTrace();
    /** This method is called from within the init() method to
     * initialize the form.
     * WARNING: Do NOT modify this code. The content of this method is
     * always regenerated by the Form Editor.
    // <editor-fold defaultstate="collapsed" desc=" Generated Code ">
    private void initComponents() {
        jLabel1 = new javax.swing.JLabel();
        jLabel1.setText("jLabel1");
        org.jdesktop.layout.GroupLayout layout = new org.jdesktop.layout.GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .add(163, 163, 163)
                .add(jLabel1)
                .addContainerGap(203, Short.MAX_VALUE))
        layout.setVerticalGroup(
            layout.createParallelGroup(org.jdesktop.layout.GroupLayout.LEADING)
            .add(layout.createSequentialGroup()
                .add(129, 129, 129)
                .add(jLabel1)
                .addContainerGap(157, Short.MAX_VALUE))
    }// </editor-fold>
    // Variables declaration - do not modify
    private javax.swing.JLabel jLabel1;
    // End of variables declaration
}I have the JRE installed. I can view other Applets in my browser, but JApplets don't work. What's going on?
Thanks

Answer 1

The error has nothing to do with your applet. The GroupLayout class is used by Matisse, the NetBeans forms editor. NetBeans should have packaged it into a jar file together with your applet class file. The HTML file that launches your applet should specify this jar file.
Here is a sample APPLET tag:
    <APPLET name="TalkHawk" ARCHIVE="TalkHawkApplet.jar" code="TalkHawkAppletPkg.TalkHawkApplet.class" width="100" height="100">
        <param name="Title" value="Magic Beans Conferencing Center">
        <param name="Logo" value="images/Logo2.jpg">
        <param name="Debug" value="0">Here is the equivalent using jsp:
    <jsp:plugin type="applet"
                archive="TalkHawkApplet.jar"
                code="TalkHawkAppletPkg.TalkHawkApplet.class"
                jreversion="1.4"
                nspluginurl="http://java.sun.com/j2se/1.4.2/download.html"
                iepluginurl="http://java.sun.com/j2se/1.4.2/download.html"
                name="TalkHawk"
                width="100"
                height="100">
        <jsp:params>
            <jsp:param name="Title" value="Magic Beans Conferencing Center" />
            <jsp:param name="Logo" value="images/Logo2.jpg" />
            <jsp:param name="Debug" value="0" />
        </jsp:params>
        <jsp:fallback>
            <p>Unable to start plugin.</p>
        </jsp:fallback>
    </jsp:plugin>