you can do this ..
call the main method of OtherApp.

ex : OtherApp.main(null); main method is static .. so it can be called like
this. you need to pass the String array as the argument or null if you are
neglecting the arguments. This will run  as a same thread.
If you want to run as another thread, create seperate thread  and call the main
method from within the run method of the thread.

Hope this answers you query.

use java.lang.reflect in a soket server that accepts main class definition from
a
port.

ex:
- u'll send "LOAD com.filika.project.runner.Runner" from soket to your server
program
- server program  'll find the main class and loads it to its vm that running
with the
help of reflect package.
- and also u can send more initial parameters with reflect ->more at:
java.sun.com

or u can define a generic interface like

public interface MyLoadable{
public void load() throws Exception;
public void start()throws Exception;
public void stop()throws Exception;
public void unload()throws Exception;

}

than u can create your apllications using this interface, making a little
expansion
to the example above.

I think you could write a little class, extended
from Thread, which will be responsible to call your
other application, like this

public class Caller extends Thread {
public void run() {
String[] parameters = new String[0];
OtherApp.main(parameters);
}
}

and then call it from your calling class:

new Caller().start();

Of course, the other app  must be in the main
application classpath. I think this shuld work