import java.util.ArrayList;
import java.util.concurrent.Exchanger;

class ExchangeTest {
  public static void main(String[] args) {
    Exchanger<ArrayList<Integer>> ex = new Exchanger<ArrayList<Integer>>();
    new Thread(new GetThread(ex)).start();
    new Thread(new PutThread(ex)).start();
    new Thread(new PutThread(ex)).start();
    new Thread(new GetThread(ex)).start();
  }
}

class GetThread implements Runnable {

  Exchanger<ArrayList<Integer>> exchanger;
  ArrayList<Integer> message;

  GetThread(Exchanger<ArrayList<Integer>> ex) {
    this.exchanger = ex;
    this.message = new ArrayList<Integer>();
    this.message.add(1);
    this.message.add(2);
    this.message.add(3);
  }

  @Override
  public void run() {
    try {
      message = exchanger.exchange(message);
      System.out.println("get thread has received " + message);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }
}

class PutThread implements Runnable {

  Exchanger<ArrayList<Integer>> exchanger;
  ArrayList<Integer> message;

  PutThread(Exchanger<ArrayList<Integer>> ex) {
    this.exchanger = ex;
    this.message = new ArrayList<Integer>();
    this.message.add(-3);
    this.message.add(-2);
    this.message.add(-1);
  }

  @Override
  public void run() {
    try {
      message = exchanger.exchange(message);
      System.out.println("put thread has received " + message);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
  }
}