'Exception in thread "main" java.lang.NoClassDefFoundError' when running java program from command line

Question

What am I doing wrong here:

class Helo { 
   // main: generate some simple output 
   public static void main (String[] args) { 
      System.out.println ("Hello, world."); // print one line 
      System.out.println ("How are you?"); // print another 
   } 
} 

When I go into terminal I do:

cd ~
javac Atempt2.java (//that's the file name) 
java Atempt2 

and then it gives me this error message:

Exception in thread "main" java.lang.NoClassDefFoundError: Atempt2

So all in all this is what I do and what happens:

david-allenders-macbook-pro:~ davidallender$ cd ~
david-allenders-macbook-pro:~ davidallender$ javac Atempt2.java
david-allenders-macbook-pro:~ davidallender$ java Atempt2
Exception in thread "main" java.lang.NoClassDefFoundError: Atempt2
david-allenders-macbook-pro:~ davidallender$ 

I am very new at this so please explain things in a very simple manner.

Thanks.

Answer 1

Its been awhile since I've done any java work but I'm pretty sure your class name needs to match your file name.