ClassNotFoundException for loading the applet

Question

I can't run this simple embedded applet.

the java.lang.ClassNotFoundException: is very clear, but I think every thing is OK.

applet code

package org.test;

import java.applet.*;
import java.awt.*;

    public class Main extends Applet
    {
        public void init()
        {}

        public void stop()
        {}

        public void paint(Graphics g)
        {
            g.drawString("Salam Applet",20,20);
        }
    }

UI code (jsp page)

<html>
<head>
    <title>salam applet</title>
</head>
<body>
<applet code="org.test.Main" width="200" height="500"></applet>
</body>
</html>

and my error at run time is

Java Plug-in 1.6.0_23
Using JRE version 1.6.0_23-b05 Java HotSpot(TM) Client VM
User home directory = C:\Users\hardcode
----------------------------------------------------
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>
----------------------------------------------------
load: class org.test.Main not found.
java.lang.ClassNotFoundException: org.test.Main
    at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
    at java.lang.ClassLoader.loadClass(Unknown Source)
    at sun.plugin2.applet.Plugin2ClassLoader.loadCode(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.io.IOException: open HTTP connection failed:http://localhost:8080/org/test/Main.class
    at sun.plugin2.applet.Applet2ClassLoader.getBytes(Unknown Source)
    at sun.plugin2.applet.Applet2ClassLoader.access$000(Unknown Source)
    at sun.plugin2.applet.Applet2ClassLoader$1.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    ... 9 more
Exception: java.lang.ClassNotFoundException: org.test.Main

this is the picture of the error in the browser. enter image description here

What is the the URL in the address bar when you visit the applet page? Note that an applet will almost certainly need to be packaged in a Jar if deployed to real world clients. — Andrew Thompson, Jun 07 '13 at 19:29
i did not try to do that, but i can see this error "Caused by: java.io.IOException: open HTTP connection failed:http://localhost:8080/org/test/Main.class" — Ammar Bozorgvar, Jun 07 '13 at 19:31
**Copy** the URL in the address bar for me. **Paste** it here. I need a base to make a point. — Andrew Thompson, Jun 07 '13 at 19:34
BTW 1) Why code an applet? If it is due due to spec. by teacher, please refer them to [Why CS teachers should stop teaching Java applets](http://programmers.blogoverflow.com/2013/05/why-cs-teachers-should-stop-teaching-java-applets/). 2) Why AWT rather than Swing? See this answer on [Swing extras over AWT](http://stackoverflow.com/a/6255978/418556) for many good reasons to abandon using AWT components. If you need to support older AWT based APIs, see [Mixing Heavyweight and Lightweight Components](http://www.oracle.com/technetwork/articles/java/mixing-components-433992.html). — Andrew Thompson, Jun 07 '13 at 19:39

score 2 · Answer 1 · answered Jun 07 '13 at 19:47

Let us imagine that the following HTML is in applet.html at the root of localhost. http://localhost:8080/applet.html.

<html>
<head>
    <title>salam applet</title>
</head>
<body>
<applet code="org.test.Main" width="200" height="500"></applet>
</body>
</html>

The code base, when not specified, points to the document base http://localhost:8080/.

Since no archive is declared, the JVM will expect the class file to be found at:

http://localhost:8080/org/test/Main.class

An 'acid test' for such a path is to copy/paste it into a browser address bar and hit Enter

You might also try opening it with Appleteer, which does more checks and produces more detailed output.

i build the project, create a war file, droped it in my tomcat, i copyed the address "http://localhost:8080/firstApplet/org/test/Main.class", and i see error 404 ?! — Ammar Bozorgvar, Jun 07 '13 at 20:13

ClassNotFoundException for loading the applet

1 Answers1