How to set focus the already running application?

Question

I am using a ServerSocket port to run one instance only of my Java Swing application, so if a user tries to open another instance of the program, i show him a warning that \

Answer 1

Since you use a server socket I assume that you use the java.net.BindException to detect that you application is already running. If you start a second instance you could send a control message which instructs you first app to normalize (if minimized) before exiting.

if (msg == BRING_TO_FRONT ) {
   frame.setState(Frame.NORMAL);
   frame.toFront();
}