- 理论:
- Class A实现接口CallBack callback——背景1
- class A中包含一个class B的引用b ——背景2
- class B有一个参数为callback的方法f(CallBack callback) ——背景3
- A的对象a调用B的方法 f(CallBack callback) ——A类调用B类的某个方法 C
- 然后b就可以在f(CallBack callback)方法中调用A的方法 ——B类调用A类的某个方法D
代码:(经典打电话例子)
package callback;
public interface CallBack {
void solve(String result);
}
package callback;
public class XiaoLi {
public void executeMessage(CallBack callBack,String question){
System.out.println("问题:"+question);
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
callBack.solve("答案是:"+2);
}
}
package callback;
public class XiaoWang implements CallBack {
//小李的引用
XiaoLi xiaoLi;
public XiaoWang(XiaoLi xiaoLi){
this.xiaoLi = xiaoLi;
}
public void askQuestion(final String question){
//线程异步
xiaoLi.executeMessage(XiaoWang.this::solve,question);
pay();
}
private void pay() {
System.out.println("我去逛街了");
}
//小王的回掉方法
@Override
public void solve(String result) {
System.out.println("小李告诉小王的答案是:"+result);
}
}
package callback;
public class CallBackTest {
public static void main(String[]args){
XiaoLi xiaoLi = new XiaoLi();
XiaoWang xiaoWang = new XiaoWang(xiaoLi);
xiaoWang.askQuestion("1+1等于几");
}
}