a observer example

ObserverExample.java

package pattern;

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

public class ObserverExample {

    public static void main(String[] args) {

        ObData ObData = new ObData();

        ObData.addObserver(new Observer() {
            @Override
            public void update(Observable o, Object arg) {
                if (o instanceof ObData) {
                    ObData ob = (ObData) o;
                    System.out.println("data is:" + ob.getData());
                    if (arg != null) {
                        System.out.println(" arg is:" + arg);
                    }
                }
            }
        });

        ObData.deliver(2);
        ObData.setData(10);
        ObData.deliver(3);
    }
}

class ObData extends Observable {

    private int data = 0;

    public int getData() {
        return data;
    }

    public void setData(int data) {
        this.data = data;
        this.deliver(data);
    }

    public void deliver(Object arg) {
        this.setChanged();
        this.notifyObservers(arg);
    }
}