public class UIThread {
    Display display;
    Shell shell;
    List<Object> list;

    // The Runnables to be executed by the UI-Thread because the other Threads ask
    // it via asyncExec(). Note that this Runnable access the list attribute of
    // the top class, in order to do it and not get a "Invalid Thread Access" it must
    // be done this way.
    private class RunnableToExec implements Runnable {
        @Override
        public void run() {
            <some work>
            list.add(new Object());
        }
    }

    // This class is just a Thread calling to the asyncExec to ask the UI-Thread
    // to execute a Runnable.
    private class ThreadCallingAsyncExec extends Thread {
        @Override
        public void run() {
            display.asyncExec(new RunnableToExec())
        }
    }

    // Entry point of the snippet.
    public static void main(String[] args) {
        ThreadCallingAsyncExec thread;

        // Create the Shell and Display.
        display = new Display()
        shell = new Shell(display);

        // Create the list where various Threads will be inserting something.
        list = new ArrayList<Object>();

        // Create a few Threads and run them.
        for (int i = 0; i < 10; i++) {
            thread = new ThreadCallingAsyncExec();
            thread.start();
        }
    }
}