java.util.concurrent.Exchanger 是用来支持两个线程之间交换数据，不支持更多线程。class represents a kind of rendezvous point where two threads can exchange objects. Here is an illustration of this mechanism:

Two threads exchanging objects via an Exchanger.

当线程A调用exchange()方法时，将会阻塞，直到另一个线程也调用此方法。以一个线程安全的方式交换数据。

例子如下

Exchanger exchanger = new Exchanger();

ExchangerRunnable exchangerRunnable1 =

new ExchangerRunnable(exchanger, "A");

ExchangerRunnable exchangerRunnable2 =

new ExchangerRunnable(exchanger, "B");

new Thread(exchangerRunnable1).start();

new Thread(exchangerRunnable2).start();

public class ExchangerRunnable implements Runnable{

Exchanger exchanger = null;

Object    object    = null;

public ExchangerRunnable(Exchanger exchanger, Object object) {

this.exchanger = exchanger;

this.object = object;

}

public void run() {

try {

Object previous = this.object;

this.object = this.exchanger.exchange(this.object);

System.out.println(

Thread.currentThread().getName() +

" exchanged " + previous + " for " + this.object

);

} catch (InterruptedException e) {

e.printStackTrace();

}

}

}