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 value has changed notify observers
        if (!watchedValue.equals(value)) {
            watchedValue = value;

            // mark as value changed
            setChanged();
        }

    }
}

class MainObserver implements Observer {
    public void update(Observable obj, Object arg) {
        System.out.println("Update called");
    }
}

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

        watched.setValue("New Value");
        if (watched.hasChanged())
            System.out.println("Value changed");
        else
            System.out.println("Value not changed");
    }
}