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

Caused by: java.lang.ClassNotFoundException: HelloWorld

        at java.net.URLClassLoader$1.run(URLClassLoader.java:200)

        at java.security.AccessController.doPrivileged(Native Method)

        at java.net.URLClassLoader.findClass(URLClassLoader.java:188)

        at java.lang.ClassLoader.loadClass(ClassLoader.java:307)

        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)

        at java.lang.ClassLoader.loadClass(ClassLoader.java:252)

        at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:320)

Could not find the main class: HelloWorld.  Program will exit.