title: How do I run Java .class files?
body: <p>I've compiled a HelloWorld program, and I'm using the command prompt to run it.  The .class file is named HelloWorld2.class</p>
  
  <p>The file is located in C:\Users\Matt\workspace\HelloWorld2\bin
  Here's what I'm getting when I go to command prompt, and type "Java HelloWorld2" :</p>
  
  <pre><code>C:\Users\Matt&gt;Java HelloWorld2
  Exception in thread "main" java.lang.NoClassDefFoundError: HelloWorld2
  Caused by: java.lang.ClassNotFoundException: HelloWorld2
          at java.net.URLClassLoader$1.run(Unknown Source)
          at java.security.AccessController.doPrivileged(Native Method)
          at java.net.URLClassLoader.findClass(Unknown Source)
          at java.lang.ClassLoader.loadClass(Unknown Source)
          at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
          at java.lang.ClassLoader.loadClass(Unknown Source)
  Could not find the main class: HelloWorld2.  Program will exit.
  </code></pre>
  
  <p>I was expecting to see a HelloWorld printed out.  What am I doing wrong?  I have the JDK installed.</p>