Question

I am new to eclipse + Java. I am trying to create executable jar file with eclipse
export option. It works very well. But in my project, I have almost 10 packages (my own) and 4 main classes. I want to create a executable jar file that can execute any of main class from 4 main classes.

For example: Double click write class name and run that class

Answer 1

Just a quick example of how to deal with command line options to launch different things, I would have put it into a reply to @serplat’s answer but then I can’t format it.

public static void main(String[] args)
{
    if(args.length == 0) {
        // Do default here--no options specified
    } else if(args.length > 2) {
        // Complain that there are too many args, or implement multi-args
    } else // known just one arg
       if(args[1].equals("option1") {
           // call the main of your first app
       } else if(args[1].equals("option2") {
           // start your second app
      ...
   }
}

There are much better ways to handle command line stuff, but this is understandable and should do what you need. Later you might look into something more flexible.