How to make GUI components feel the state of other objects?

Question

I need my JButtons in any place of GUI be enabled or disabled depend on states of several objects or events generated by some other objects. Would you recommend the common approach of how it can be implemented in Swing?

Answer 1

Sorry for the delay, but the job that pay my bills is keeping me very busy today (taking a short break to reply to you) :)
Yes, the observers observable pattern is a good way to decouple this (but it could be overkill if you only want to update the status of one button). You will need to have references to the button variable so you can enable it / disable it from another place. For example, let's say you have an Class that extends the Observable and performs your heavy processing on a separate thread (Please not than I don't use generics here, just trying to quickly show you how you may want to do this):
import java.util.Observable;
public class TaskMan extends Observable {
    private List comp; 
    public void TaskMan (final List aComp) {
        comp = aComp; // Keep track of the components you want to to toggle on / off
    public void notifyObservers(Object arg) {
            setChanged(true);
            super.notifyObservers(arg);
    public void doIt() {
        new Thread (new Runnable() {
             public void run() {
                     notifyObservers(comp); // Dissable
                     // Your long consumming task here
                    notifyObservers(comp); // Enable
}Then you have the Observer class that enable / dissable the buttons and other components:
import java.util.Observer;
import java.awt.Component;
public class MyObserver implements Observer {
     public void update(Object observable, Object arg) {
             if (! (arg instanceof List)) {
                 return;
             List list = (List) arg;
             for (Object elem: list) {
                    Component comp = (Component) elem;
                    EventQueue.invokeLater(new Runnable() {
                           public void run() {
                                 comp.setEnabled(! comp.isEnabled());
}And finally your main class, where you create and put together your GUI, register your observers and you call your long time consuming job
import java.util.*;
public class MyApp {
    public static void main(String [] args) throws Exception {
              List comps = new ArrayList();
              JButton aBtn = new JButton("Hey dude!");
              comps.add(aBtn);
              TaskMan task = new TaskMan(comps);
              task.addObserver(new MyObserver());
              task.doIt();
}Looks like you have several use cases there, maybe you want to try this approache first for some of them, adding more logic to the observer.
Please reply back, let me know what you think.
Regards,
Jose.