are you having problems compiling (javac) or running(
java) it? Make sure you have the case of the filename EXACTLY match the case inside the file. in other words, if you have in your code:
you must have the file named "HelloWorld.java". It will not work if you have "helloWorld.java" or anything else. also, make sure you are spelling it right - in your post, you called it "h
alloworld.java".
These little details matter in Java.
There are only two hard things in computer science: cache invalidation, naming things, and off-by-one errors