线程按序交替

线程按序交替

package com.atguigu.juc; import java.util.concurrent.locks.Condition; import java.util.concurrent.locks.Lock; import java.util.concurrent.locks.ReentrantLock; /* * 编写一个程序，开启 3 个线程，这三个线程的 ID 分别为 A、B、C，每个线程将自己的 ID 在屏幕上打印 10 遍，要求输出的结果必须按顺序显示。 * 如：ABCABCABC…… 依次递归 */ public class TestABCAlternate { public static void main(String[] args) { AlternateDemo ad = new AlternateDemo(); new Thread(new Runnable() { @Override public void run() { for (int i = 1; i <= 20; i++) { ad.loopA(i); } } }, "A").start(); new Thread(new Runnable() { @Override public void run() { for (int i = 1; i <= 20; i++) { ad.loopB(i); } } }, "B").start(); new Thread(new Runnable() { @Override public void run() { for (int i = 1; i <= 20; i++) { ad.loopC(i); System.out.println("-----------------------------------"); } } }, "C").start(); } } class AlternateDemo{ private int number = 1; //当前正在执行线程的标记 private Lock lock = new ReentrantLock(); private Condition condition1 = lock.newCondition(); private Condition condition2 = lock.newCondition(); private Condition condition3 = lock.newCondition(); /** * @param totalLoop : 循环第几轮 */ public void loopA(int totalLoop){ lock.lock(); try { //1. 判断 if(number != 1){ condition1.await(); } //2. 打印 for (int i = 1; i <= 1; i++) { System.out.println(Thread.currentThread().getName() + "\t" + i + "\t" + totalLoop); } //3. 唤醒 number = 2; condition2.signal(); } catch (Exception e) { e.printStackTrace(); } finally { lock.unlock(); } } public void loopB(int totalLoop){ lock.lock(); try { //1. 判断 if(number != 2){ condition2.await(); } //2. 打印 for (int i = 1; i <= 1; i++) { System.out.println(Thread.currentThread().getName() + "\t" + i + "\t" + totalLoop); } //3. 唤醒 number = 3; condition3.signal(); } catch (Exception e) { e.printStackTrace(); } finally { lock.unlock(); } } public void loopC(int totalLoop){ lock.lock(); try { //1. 判断 if(number != 3){ condition3.await(); } //2. 打印 for (int i = 1; i <= 1; i++) { System.out.println(Thread.currentThread().getName() + "\t" + i + "\t" + totalLoop); } //3. 唤醒 number = 1; condition1.signal(); } catch (Exception e) { e.printStackTrace(); } finally { lock.unlock(); } } }