ObservedObject.java Source code

Introduction

Here is the source code for ObservedObject.java

Source

import java.util.Observable;
import java.util.Observer;

class ObservedObject extends Observable {
    private String watchedValue;

    public ObservedObject(String value) {
        watchedValue = value;
    }

    public void setValue(String value) {
        if (!watchedValue.equals(value)) {
            System.out.println("Value changed to new value: " + value);
            watchedValue = value;

            setChanged();
            notifyObservers(value);
        }
    }
}

class MainObserver implements Observer {

    public void update(Observable obj, Object arg) {
        System.out.println(obj + "called with Arguments: " + arg);
    }
}

public class Main {
    public static void main(String[] args) {
        ObservedObject watched = new ObservedObject("Original Value");

        MainObserver watcher1 = new MainObserver();
        MainObserver watcher2 = new MainObserver();

        watched.addObserver(watcher1);
        watched.addObserver(watcher2);

        int count = watched.countObservers();
        System.out.println(count + " observers listening");

        watched.setValue("New Value");

        watched.deleteObserver(watcher1);
        count = watched.countObservers();
        System.out.println(count + " observers listening");

        watched.setValue("Latest Value");
    }

}