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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();		}	}	}

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