public class TestRunnable {
    public static void main(String[] args) {
        MyRunnable runnable = new MyRunnable();
        Thread thread = new Thread(runnable);
        thread.start();
    }
}

class MyRunnable implements Runnable {
    int id = -1;

    public MyRunnable() {}

    public MyRunnable(int id) {
        this.id = id;
    }

    @Override
    public void run() {
        try {
            Thread.sleep(1000);
        } catch (Exception e) {
            e.printStackTrace();
        }
        System.out.println(id == -1 ? "Finished." : ("Thread " + id + " finished."));
    }
}