public interface EventObserver {
    void event();
}


public interface EventObserverManager {
    void registerEventObserver(Class clazz, EventObserver eventObserver);
    void removeEventObserver(Class clazz, EventObserver eventObserver);
    void notifyAll(Class clazz);
}

public class EventObserverManagerImpl implements EventObserverManager {
    private final Map<Class, Set<EventObserver>> observersMap = new HashMap<Class, Set<EventObserver>>();

    @Override
    public void registerEventObserver(Class clazz, EventObserver eventObserver) {
        getObserverSet(clazz).add(eventObserver);
    }

    @Override
    public void removeEventObserver(Class clazz, EventObserver eventObserver) {
        remoteObserver(clazz, eventObserver);
    }

    @Override
    public void notifyAll(Class clazz) {
        for (EventObserver eventObserver : observersMap.get(clazz)) {
            eventObserver.event();
        }
    }

    //----------------------------------------------------
    public void click(Class clazz) {
        notifyAll(clazz);
    }

    //----------------------------------------------------
    private Set<EventObserver> getObserverSet(Class clazz) {
        Set<EventObserver> result = observersMap.get(clazz);
        if (result == null) {
            result = new HashSet<EventObserver>();
            observersMap.put(clazz, result);
        }
        return result;
    }

    private void remoteObserver(Class clazz, EventObserver eventObserver) {
        Set<EventObserver> observerSet = getObserverSet(clazz);
        if (observerSet.contains(eventObserver)) {
            observerSet.remove(eventObserver);
        }
    }
}

public class Frame1 extends JFrame {
    public Frame1(final EventObserverManager eventObserverManager) {
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        JButton button = new JButton("iButton");
        ActionListener actionListener = new ActionListener() {
            @Override
            public void actionPerformed(ActionEvent e) {
                eventObserverManager.notifyAll(Frame1.class);
            }
        };
        button.addActionListener(actionListener);
        add(button);
    }
}

public class Frame2 extends JFrame implements EventObserver {
    private final JTextArea jTextArea;

    public Frame2(final EventObserverManager eventObserverManager) {
        setVisible(true);
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        eventObserverManager.registerEventObserver(Frame1.class, this);
        jTextArea = new JTextArea();
        jTextArea.setText(String.valueOf(System.currentTimeMillis()));
        add(jTextArea);
    }

    @Override
    public void event() {
        jTextArea.setText(String.valueOf(System.currentTimeMillis()));
    }
}

public class Start {
    public static void main(String[] args) {
        EventObserverManager eventObserverManager = new EventObserverManagerImpl();
        Frame1 frame1 = new Frame1(eventObserverManager);
        Frame2 frame2 = new Frame2(eventObserverManager);
    }
}