java回调机制

 1 public class A {
 2     B personB = new B();
 3     public void question(int input1,int input2){
 4         personB.waitAnswer(input1, input2, new CallbackListener() {
 5             @Override
 6             public void callback(int result) {
 7             System.out.println("B 回答：" + result);
 8             }
 9         });
10 
11 }
12 
13 public static void main(String[] args) {
14     A personA = new A();
15     System.out.println("A向B提问");
16     personA.question(1,2);
17     System.out.println("在B告诉我答案之前我先做点别的事情");
18     }
19 }

 1 package callback;
 2 
 3     public class B {
 4         public void waitAnswer(final int a, final int b,
 5                                         final CallbackListener listener){
 6             new Thread(new Runnable() {
 7                 @Override
 8                 public void run() {
 9                     int c = a + b;
10                     listener.callback(c);
11                 }
12            }).start();
13         }
14     }

1 package callback;
2 
3 public interface CallbackListener {
4 
5     public void callback(int result);
6 
7 }