以下是一些示例代码，可以帮助你入门：
import java.util.*;// An interface to be implemented by everyone interested in "Hello" eventsinterface HelloListener { void someoneSaidHello();}// Someone who says "Hello"class Initiater { private List<HelloListener> listeners = new ArrayList<HelloListener>(); public void addListener(HelloListener toAdd) { listeners.add(toAdd); } public void sayHello() { System.out.println("Hello!!"); // Notify everybody that may be interested. for (HelloListener hl : listeners) hl.someoneSaidHello(); }}// Someone interested in "Hello" eventsclass Responder implements HelloListener { @Override public void someoneSaidHello() { System.out.println("Hello there..."); }}class Test { public static void main(String[] args) { Initiater initiater = new Initiater(); Responder responder = new Responder(); initiater.addListener(responder); initiater.sayHello(); // Prints "Hello!!!" and "Hello there..." }}
