How to determine when an application started using java reflection has completed

Question

Hello developers!

I have a Java program that uses reflection to find and invoke the main(String[] args) method of another Java program. This other program is usually a Swing App that tends to spawn its own threads. I was wondering if there was a way to determine when this other 'program' terminates. I'm not sure if there is anyway to detect this since it executes in the same space as the host program. The current method is just to check if any of the frames open aren't our own, not exactly the greatest solution. Running the child program in its process also isn't really an option since we access to it.

EDIT: It looks the answer is a dual approach. First create a ThreadGroup and launch the child program in a thread that is a member of that group. Then make sure to check Frame.getFrames() if any of the frames belong to child.

Thank you, --Sandro

Answer 1

Start the child app in a separate ThreadGroup (probably best set it up as a daemon thread group) and periodically check whether it contains any running threads or subgroups.

Answer 2

If you have ways to discover the windows this child application is using you could just attach the appropriate Window listeners and wait for all the close event.

Edit:

Using the event listener approach at least allows you to not loop and query constantly for the frames. For the case of the spawned threads I have no clue. If there is a way you could track your own threads and discover the app's threads you could do the same looping as for the Frames.

Edit 2:

What comes into my mind is to use JMX on yourself to get the threads and other information, but I don't know JMX in much detail.