Running code on the main thread from a secondary thread?

Question

This is a general Java question and not an Android one first off!

I\'d like to know how to run code on the main thread, from the context of a secondary thread. For e

Answer 1

There is no universal way to just send some code to another running thread and say "Hey, you, do this." You would need to put the main thread into a state where it has a mechanism for receiving work and is waiting for work to do.

Here's a simple example of setting up the main thread to wait to receive work from other threads and run it as it arrives. Obviously you would want to add a way to actually end the program and so forth...!

public static final BlockingQueue queue = new LinkedBlockingQueue();

public static void main(String[] args) throws Exception {
    new Thread(new Runnable(){
        @Override
        public void run() {
            final int result;
            result = 2+3;
            queue.add(new Runnable(){
                @Override
                public void run() {
                    System.out.println(result);
                }
            });
        }
    }).start();

    while(true) {
        queue.take().run();
    }
}