Java Observer Pattern not notifying

Question

For some reason my observers are not being notified when i call the notifyObserver methods, using the java.util.Observable objects:

here is my observable object:

public class ProjectManager extends Observable { ... public void updateProjects(String project, String pack, String source, String ARN) { ... if(newSource) { tempPack.add(tempSource); System.out.println("Notify observers: " + this.countObservers()); this.notifyObservers(); } ... }

i can see from my output that the observer is being added but not being notified.

and my observer object looks like this:

public class IDE implements Observer { @Override public void update(Observable o, Object arg) { System.out.println("Notified"); }

For some strange reason the observable object is not being notified at all. Am i doing something wrong here?

Jacob is on Codidact · Accepted Answer · 2012-07-03 16:44:32Z

15

You need to setChanged before you notifyObservers

answered Jul 3, 2012 at 16:44

Jacob is on Codidact

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2 Comments

Ted Hopp Over a year ago

+1. Another reason to dislike Java's Observable implementation.

Paul Rooney Over a year ago

bit of a major gotcha but I guess it might make sense from a transactional point of view.

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