I wrote a little program in java just to test whether everything was working well since I haven't tried using java with linux before. My program is as follows:

import javax.swing.JOptionPane;

public class test
{
public static void main(String args[])
{
JOptionPane.showMessageDialog(null, "Works");
System.exit(0);
}
}

It compiles fine, but when I run java test, I get "Exception in thread "main" java.lang.NoClassDefFoundError at ....[a lot of classes are defined after this at]" I thought it was because I didn't have gnome installed and I was running just from command prompt, but it won't work now that I have gnome installed either. Any ideas? Thanks

did you name the file test.java? the file name must match the class contained in the file (case sensitive I believe)

Good Luck!

Do you have your PATH and JAVA_HOME environment variables set?

To use the swing classes of java, the gui environment has to be installed in linux. Is it?

To answer all of your questions in the hope of figuring this out. Yes, I have named it test.java and it compiled fine.

I have the PATH set to $PATH:$HOME/bin:/sbin:/home/myusername/java/bin/:/home/myusername/java/jre:$HOME/seti. I am not sure what the first and last ones are set to, but they were there when I opened my .bash_profile. If you can explain that too it would be great.

Finally, I have installed the gnome environment and have tried to run it from there, but I don't know if there is a seperate gui package that needs to be installed.

Thanks again for the help.

You installed Java to your home directory? That is just fine, but it is a touch unusual. If that is so, then your PATH is set correctly. Now you probably need to set your JAVA_HOME environment variable. You need that pointing to the entire Java directory. So in your case it would be:

JAVA_HOME = /home/username/java
export JAVA_HOME

I'd put these lines in the same file you use to set your PATH and you may have to log out and back in for this to take hold.

I appreciate the help, but that didn't seem to correc the problem either. Maybe I am jsut missing something.

id never programmed java before a few days ago and i was having a discussion with someone - if typecasting a double to an int rounded, he said it did so i set about to show him it didnt, i wrote my first java program(to demonstrate this) in about 3mins, i then compiled it, had to sort out a few errors, then it took me an over an hour to make it run. you see the problem was i was typing 'java roundtest.class' to run it, which made sense to me because the file i wanted to run was called roundtest.class but for some strange reason to run roundtest.class you type 'java roundtest'

the point here is - type 'java test' instead of 'java test.class' and it'll run fine.

Yeah, it could be something silly. When I run into troubles like this, it usually is something completely dumb . Your code is fine. I just ran it on my machine without a problem, so we need to look at how you compile and run it.

I know this sounds stupid, but could you post the exact commands you use to compile it and the exact command you use to run it and the full error messages you get?