可以在对中对元素进行配对和交换的线程的同步点，类似于交易，A拿着钱到达指定地点，B拿着物品到达指定地点，相互交换，然后各自忙各自的事去了。
1 package ch03; 2 3 import java.util.concurrent.Exchanger; 4 5 public class ExchangerTest { 6 7 public static void main(String[] args) { 8 final Exchanger<String> changer = new Exchanger<>(); 9 new Thread(new Runnable() { 10 11 @Override 12 public void run() { 13 try{ 14 String data1 = "xyy"; 15 System.out.println("交换前，"+Thread.currentThread().getName()+"的数据是："+data1); 16 //等待交易 17 String afterChange = changer.exchange(data1); 18 System.out.println("交换后，"+Thread.currentThread().getName()+"的数据是："+afterChange); 19 }catch (Exception e) { 20 } 21 } 22 }).start(); 23 24 new Thread(new Runnable() { 25 26 @Override 27 public void run() { 28 try{ 29 String data1 = "zy"; 30 System.out.println("交换前，"+Thread.currentThread().getName()+"的数据是："+data1); 31 //等待交易 32 String afterChange = changer.exchange(data1); 33 System.out.println("交换后，"+Thread.currentThread().getName()+"的数据是："+afterChange); 34 }catch (Exception e) { 35 } 36 } 37 }).start(); 38 } 39 40 }