Exception in thread "main" java.lang.NoClassDefFoundError

If you run you java program in the following manner:

You will get the java.lang.NoClassDefFoundError.  This error occurs because it is looking for the myprogram.class Class within your file.  To fix this, run your java program in this fashion:

Do not append the .class to the end of the file.

This error will also be thrown if the java compiler cannot find a class that is referenced through an import statement.  Make sure all import files are in your class path, or you must specify them explicitly with the -classpath parameter when you compile.