observer 패턴

package com.example.studytest;

import java.util.ArrayList;

import java.util.Iterator;

import android.app.Activity;

import android.os.Bundle;

import android.util.Log;

public class ObserverSample extends Activity {

@Override

protected void onCreate(Bundle savedInstanceState) {

// TODO Auto-generated method stub

super.onCreate(savedInstanceState);

Calculater cal = new Calculater();

cal.add(new AllObserver());

cal.add(new HighObserver());

cal.plus(5);

cal.minus(2);

cal.plus(15);

}

interface Observer {

abstract void update(Calculater action);

}

class AllObserver implements Observer {

public void update(Calculater cal) {

// TODO Auto-generated method stub

Log.d("test", "ALL : " + String.valueOf(cal.getResult()));

}

}

class HighObserver implements Observer {

public void update(Calculater cal) {

// TODO Auto-generated method stub

if (cal.getResult() > 10) {

Log.d("test", "High : " + String.valueOf(cal.getResult()));

}

}

}

class Calculater {

ArrayList<Observer> observers = new ArrayList<Observer>();

int i = 0;

void add(Observer ob) {

observers.add(ob);

}

void remover(Observer ob) {

observers.remove(ob);

}

void notifys() {

Iterator<Observer> it = observers.iterator();

while (it.hasNext()) {

Observer o = it.next();

o.update(this);

}

}

int getResult() {

return i;

}

void minus(int n) {

i-=n;

}

void plus(int n) {

i+=n;

}

}

}