ParserException error (newbie question)

Hello all.

I have a newbie question that I hope you can help me with:
I'm using Ubuntu 10.04 and I have just installed the package 
libhtmlparser-java. I get no errors when compiling the code below 
(test_htmlparser.java) using the command

$ javac -classpath /usr/share/java/libhtmlparser.jar test_htmlparser.java

but when I try to run the program, I get the following error:

$ java test_htmlparser
Exception in thread "main" java.lang.NoClassDefFoundError: 
org/htmlparser/util/ParserException
	at test_htmlparser.main(test_htmlparser.java:12)
Caused by: java.lang.ClassNotFoundException: 
org.htmlparser.util.ParserException
	at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
	... 1 more



What can I do to fix this?

/Andreas


----- test_htmlparser.java begin -----

import org.htmlparser.*;
import org.htmlparser.util.*;

class test_htmlparser
{
     public static void main(String[] args)
     {
	try {
	    Parser parser = new Parser("http://www.sslug.dk");
	} catch (ParserException e) {
	    System.err.println("Caught ParserException: " + e.getMessage());
	}

     }
}

----- test_htmlparser.java end -----

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