被观察对象、观察者
public interface Subject {
void addListner(Listener listener);
void removeListner(Listener listener); void advice();
}
public interface Listener { void update();
}
import java.util.ArrayList;import java.util.Iterator;import java.util.List;
public class ConcreteSubject implements Subject {
private List<Listener> list = new ArrayList<Listener>();
public void addListner(Listener listener) { list.add(listener);
}
public void removeListner(Listener listener) { list.remove(listener);
} public void advice() { Iterator<Listener> listIterator = list.iterator(); while (listIterator.hasNext()) { Listener listener=listIterator.next(); listener.update(); }
}
}
