can't able to run java program

hello friends,
I am a begginner to learn java.I am able to compile the program using

executable file by giving " javac helloworld.java " .
Its worked fine and created a class file in the same directory.
But, when tried to run using the statement " java helloworld " ,
I am repeatedly getting the following error.
Exception in thread "main" java.lang.NoClassDefFoundError: helloworld
I think u can understand my problem.
Help me to learn java..

Waiting for ur replies..
thank u...
bye..

Hi 'Java Gal'.

Your display name doesn't match our naming guidelines. Please change it to a 'real name'. http://www.javaranch.com/name.jsp

And this is a Servlet Forum. Your program is well.. "hello world". So I'll move this to Java In General - Beginner's Forum. You'll find plenty of help there.

It seems you have not set the classpath properly .
Also add '.' ( for current directory ) in the classpath .

It doesn't seem like a path problem to me, perhaps you want to double check your main method signature, it should be
public static void main(String[] args) { }

Lakshmi,
Welcome to JavaRanch!
We ain't got many rules 'round these parts, but we do got one. Please change your display name to comply with The JavaRanch Naming Policy.
Note that we require display names of the format First Name(s) + SPACE + Last Name.
Thanks Pardner! Hope to see you 'round the Ranch!
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As suggested above, your problem likely stems around the CLASSPATH value.
If you use the following command, does the program run?
java -classpath . helloworld