问题描述

一道选择题：这一小段代码允许各种数据库的操作，下面四个选项哪个正确

public final class MyClass {

            private Connection connection;

            public Example(Connection c){
                this.connection = c;
            }

            public interface ConnectionWorker{
                void doSomething(Connection conn);
            }

            public void work(ConnectionWorker worker){
                worker.doSomething(connection);
            }

}

(A) Example can be subclassed in order to specialize the implementation of MyClass.work(ConnectionWorker)
(B) Specialization is achieved through implementation of a ConnectionWorker
(C) The call to worker.doSomething must be synchronized on worker
(D) worker.doSomething must launch a worker thread passing conn and then wait with Thread join

解决方案

A是错的，因为这是final class，CD在代码中没有提到。看上去应该选B。通过实现ConnectionWorker接口并且传给work方法实现对doSomething的Specialization。