java的回调

java的回调

1，明确什么是回调方法

2，采用接口来实现回调

java同步回调 

一个类实现了接口，将他传递给另一个类，在另一个类调用接口中方法

public class Bar implements Foo.FooCallback {

    public void eatFood() {
        System.out.println("in eatFood() ");
    }

    //这是回调方法
    @Override
    public void eat(String food) {
        System.out.println("【@】" + food);
    }

}

public class Foo{
    
   public FooCallback fooCallback;

   public Foo(FooCallback fooCallback) {
       this.fooCallback = fooCallback;
   }
   
   public interface FooCallback{
       public void eat(String food);
   }
   
   public void say() {
       fooCallback.eat("西安蛋炒饭");
   }
   
}

public class demo {
    public static void main(String args[]) {
        Bar bar = new Bar();
        Foo foo = new Foo(bar);
        foo.say();
    }
}

 

java异步回调

其实和同步回调差不多，只是新开线程，然后在新线程中回调接口中的方法

public interface EatRice {
   public void eat(String food);
}

public class XiaoMing implements EatRice {

    public void say() {

    }

    @Override
    public void eat(String food) {
        System.out.print("小明和小李一起去吃" + food);
    }
}

public class XiaoLi {// 小李

    protected EatRice er;

    public void setEatRiceListener(EatRice er, String food) {
        this.er = er;
        washFace(food);
    }

    public void washFace(String food) {

        System.out.print("小李要洗漱");

        new Thread(new Runnable() {

            @Override
            public void run() {
                try {
                    // 小李洗漱的同时小明玩手机，开启线程实现异步
                    play();
                    
                    Thread.sleep(10000);
                    System.out.print("10秒后 ");
                    // B调用A的方法
                    er.eat(food);
                } catch (InterruptedException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }
            }
        }).start();
    }

    public void play() {
        System.out.println(" 小明要玩手机");
    }

}

    public static void main(String[] args) {
        
        EatRice er = new XiaoMing();
        new XiaoLi().setEatRiceListener(er, "小龙虾");
    }