package observer.six;
import java.util.List;
import java.util.ArrayList;

public class Main {
	public static void main(String[] argv) {
		Int c = new Int();
		c.addObserver(new IntObserver());
		Runnable r1 = new M(c);
		Runnable r2 = new N(c);
		for (int i=0; i<10000; i++) {
			r1.run();
			r2.run();
		}
	}
}

interface Observer {
	public void update();
}

class IntObserver implements Observer {
	private int numOps;
	public void update() {
		System.out.println (++numOps);
	}
}
class Int {
	private List<Observer> observers = new ArrayList<Observer>();
	private boolean changed = false;
	public void addObserver(Observer o) {
		observers.add(o);
	}
	private void setChanged() {
		changed = true;
	}
	private void notifyObservers() {
		if (changed) {
			for (Observer o : observers) {
				o.update();
			}
			changed = false;
		}
	}
	private int v;
	public int get() { return v; }
	public void inc() { v++; setChanged(); notifyObservers(); }
	public void dec() { v--; setChanged(); notifyObservers(); }
}
class M implements Runnable {
	private Int c;
	public M(Int c) { this.c = c; }
	public void run() {
		c.inc();
		c.inc();
		c.dec();
	}
}
class N implements Runnable {
	private Int c;
	public N(Int c) { this.c = c; }
	public void run() {
		for (int i=0; i<50; i++) {
			if (i%3==0) {
				c.dec();
			} else {
				c.inc();
			}
		}
	}
}