简介
观察者模式用于将两个耦合的对象以事件的方式进行分离，从而降低其耦合度。
示例
public class Observable {
private List<Observer> observers;
public Observable() {
observers = new ArrayList<>();
}
public void add(Observer observer) {
this.observers.add(observer);
}
public void notify() {
this.notify(null);
}
public void notify(Object msg) {
for (Observer observer : observers) {
observer.update(this, msg);
}
}
}
public interface Observer {
void update(Observable o, Object msg);
}
public class Main {
public static void main(String[] args) {
Observable observable = new Observable();
observable.add(new AObserver());
observable.add(new BObserver());
observable.notify("hello observer!");
}
}
