当对象的状态发生变化时,在Java中触发事件

import java.util.EventObject;

// 定义事件类
class MyEvent extends EventObject {
    private String message;

    public MyEvent(Object source, String message) {
        super(source);
        this.message = message;
    }

    public String getMessage() {
        return message;
    }
}

// 定义事件监听器接口
interface MyEventListener {
    void handleEvent(MyEvent event);
}

// 定义事件源类
class MyObject {
    private MyEventListener listener;

    public void setEventListener(MyEventListener listener) {
        this.listener = listener;
    }

    public void doSomething() {
        // 对象状态发生变化时触发事件
        if (listener != null) {
            MyEvent event = new MyEvent(this, "Object state changed");
            listener.handleEvent(event);
        }
    }
}

// 实现事件监听器接口
class MyListener implements MyEventListener {
    @Override
    public void handleEvent(MyEvent event) {
        System.out.println("Event received: " + event.getMessage());
        // 执行相应的操作
    }
}

public class Main {
    public static void main(String[] args) {
        MyObject obj = new MyObject();
        MyListener listener = new MyListener();
        obj.setEventListener(listener);

        // 当对象状态发生变化时，触发事件
        obj.doSomething();
    }
}