线程辅助类（一）--Exchanger

线程辅助类Exchanger通常用于在两个线程间，在某一同步点，进行数据交换。

一、关键点如下：

1、泛型定义数据交换的类型，如Exchanger<String> exchanger = new Exchanger<>()；

2、 exchanger.exchange(data),进行数据交换，参数是用去交换的数据，返回值是交换回来的结果；

二、实例如下：

public class ExchangerMain {    public static void main(String[] args) {        ExecutorService es = Executors.newFixedThreadPool(2);        Exchanger<String> exchanger = new Exchanger<>();        es.submit(new ThreadOne(exchanger));        es.submit(new ThreadTwo(exchanger));        es.shutdown();    }    static class ThreadOne implements Callable<String>{        private Exchanger<String> exchanger;        public ThreadOne(Exchanger<String> exchanger) {            this.exchanger = exchanger;        }        @Override        public String call() throws Exception {            String data = "one";            System.out.println(Thread.currentThread().getName() + " wait change data : "+data);            String newData = exchanger.exchange(data);            System.out.println(Thread.currentThread().getName()+ " change data success ,newData : "+ newData);            return null;        }    }    static class ThreadTwo implements Callable<String>{        private Exchanger<String> exchanger;        public ThreadTwo(Exchanger<String> exchanger) {            this.exchanger = exchanger;        }        @Override        public String call() throws Exception {            String data = "two";            System.out.println(Thread.currentThread().getName() + " wait change data : "+data);            String newData = exchanger.exchange(data);            System.out.println(Thread.currentThread().getName()+ " change data success ,newData : "+ newData);            return null;        }    }}

运行结果：

pool-1-thread-1 wait change data : one
pool-1-thread-2 wait change data : two
pool-1-thread-2 change data success ,newData : one
pool-1-thread-1 change data success ,newData : two