You might have encountered following error message when trying to run an executable jar file.

Java Code:
Java Virtual Machine Launcher
Could not find the main class. Program will exit!
This occurs because Manifest file is either missing or dose not contain the class name which has the main method.

Java Code:
Manifest-Version: 1.2
Main-Class: MainClassName
Created-By: 1.4 (Sun Microsystems Inc.)