you will have to explain your problem a lot better than you have been
1.
August 7, to which you received a reply, but no follow-up to say it didn't
work or it wasn't what you wanted etc
2.
August 18, this
thread, again a reply asking for more info/clarification,
only follow-up a month later as a new post.
3.
September 16, new post (follow-up to 2.) with a little extra info.
OK, working on this
> I want to control once instance of an app with another instance of the same app.
I have no idea what you are trying to do here, perhaps you can demonstrate
with this sample program.
compile it, then jar it, then double click the .jar file 3 times.
there will now be 3 small applications on your desktop, each with a
textfield and a button. lets say you enter "Hello World" into the left-most
app's textfield, then click the adjacent button.
What do you want to happen when the button is clicked
(note: the left most app. might not be the first app.)