title: Error when I try to change the class name
body: <pre><code>class HelloObject {
      void speak() {
          System.out.println("Hello (from object)!");
      }
  }
  class HelloTester {
      public static void main(String[] args) {
          HelloObject object = new HelloObject();
          object.speak();
      }
  }
  </code></pre>
  
  <p>When I change the "HelloTester" class name to something like "HelloTester2", the program suddenly works. The class file is called ClassesBegin.java.</p>
  
  <p>Why does the java program not work when I try to change the name of the class?</p>
  
  <p>EDIT: Sorry I should have clarified more. I changed the class name to HelloTestera and this is the error I get:
  Exception in thread "main" java.lang.NoClassDefFoundError: HelloTester
  But it works even when the file name has nothing to do with a class name. It works with HelloTester when the file name is ClassesBegin.java</p>