Exception in thread "main" java.lang.NoClassDefFoundError:

I have problem with java. Here's the detail:

$ ls /usr/local/j2sdk1.4.2_03/
COPYRIGHT README bin jre src.zip
LICENSE README.html demo lib
LimeWireLinux.bin THIRDPARTYLICENSEREADME.txt include man

$ echo $PATH
/usr/local/OpenOffice:/usr/local/j2sdk1.4.2_03/bin:/home/knight/bin:/usr/local/bin:/usr/bin:/bin:/usr/X11R6/bin:/usr/games:/opt/kde/bin:/usr/lib/qt-3.2.2/bin:/usr/share/texmf/bin:.

$ echo $JAVA_HOME
/usr/local/j2sdk1.4.2_03

$ echo $CLASSPATH
/home/knight/work/java

$ pwd
/home/knight/work/java

$ ls
HelloWorldApp.java

$ vim HelloWorldApp.java

/**
 * The HelloWorldApp class implements an application that
 * simply displays "Hello World!" to the standard output.
 */
class HelloWorldApp {
    public static void main(String[] args) {
        System.out.println("Hello World!"); // Display "Hello World!"
    }
}

$ javac HelloWorldApp.java
$

$ java HelloWorldApp.class
Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorldApp/class

Any idea???????

Help. I want to learn java programming.

Try:

$ java HelloWorldApp

This should work.

Thanks. I am so dumb. I didn't notice this different. Oh.....