Java - switching back to main thread?

Question

How can I switch back to main thread from a different thread when there is an exception. When an exception is raised on a child thread, I want a notification to be sent to main thread and execute a method from the main thread. How can I do this?

Thanks.

Additional information

I am calling a method from my main method and starting a new thread there after some calculations and changes

Thread thread = new Thread() {
    @Override
    public void run() {
        .....
    }
}
thread.start();

Answer 1

When the exception occurs in the child thread, what is the main thread going to be doing? It will have to be waiting for any errors in a child thread.

You can establish an UncaughtExceptionHandler in the child thread, which can raise an event that the main thread is waiting for.

Answer 2

As TofuBeer says you need to provide more context, if however that context is that you're a swing app...

SwingUtilities.invokeLater(Runnable r) allows you to call back on Swing's main execution thread.

} catch (final Exception e) {
    SwingUtilities.invokeLater(new Runnable(){
        public void run() {
           //do whatever you want with the exception
        }
    }); 
}

Answer 3

If your child thread was created in the main, you might leave the exception pop up and handle it on the main thread.

You can also put a sort of call back.

I haven't tried this my self though.