三个线程轮流执行顺序打印ABC java基础

方法1:使用boolean标记

package com.ziyear.exam; /** * 3个线程,顺序打印ABC10次 */ public class PrintThread_ABC_10_1 { /* 定义标记,初始1为true; 2,3为false->可以打印A, 打印完设置2为true; 1,3为false->可以打印B 打印完设置3为true; 1,2为false->可以打印C 打印完设置1为true; 2,3为false->可以打印A ........每个线程各自循环10次 */ private static boolean flag1 = true; private static boolean flag2 = false; private static boolean flag3 = false; public static void main(String[] args) { final PrintThread_ABC_10_1 o = new PrintThread_ABC_10_1(); //创建一个final的本对象用来加锁 Thread t1 = new Thread(() -> { for (int i = 0; i < 10; i++) {//循环10次 while (true){ synchronized (o){ if(!flag1){//如果第一个标记为false时等待 try { o.wait(); } catch (InterruptedException e) { e.printStackTrace(); } }else{ System.out.println(Thread.currentThread().getName()); flag1 = false; flag2 = true; flag3 = false; o.notifyAll(); //唤醒所有线程 break; } } } } },"A"); Thread t2 = new Thread(() -> { for (int i = 0; i < 10; i++) {//循环10次 while (true){ synchronized (o){ if(!flag2){//如果第一个标记为false时等待 try { o.wait(); } catch (InterruptedException e) { e.printStackTrace(); } }else{ System.out.println(Thread.currentThread().getName()); flag1 = false; flag2 = false; flag3 = true; o.notifyAll(); //唤醒所有线程 break; } } } } },"B"); Thread t3 = new Thread(() -> { for (int i = 0; i < 10; i++) {//循环10次 while (true){ synchronized (o){ if(!flag3){//如果第一个标记为false时等待 try { o.wait(); } catch (InterruptedException e) { e.printStackTrace(); } }else{ System.out.println(Thread.currentThread().getName()); flag1 = true; flag2 = false; flag3 = false; o.notifyAll(); //唤醒所有线程 break; } } } } },"C"); t1.start(); t2.start(); t3.start(); }}

【三个线程轮流执行顺序打印ABC】?
方法2:使用原子操作类AtomicInteger

package com.ziyear.exam; import java.util.concurrent.atomic.AtomicInteger; /** * 3个线程,顺序打印ABC10次 */ public class PrintThread_ABC_10_2 { static AtomicInteger synObj = new AtomicInteger(0); public static void main(String[] args) { TestPrint t1 = new TestPrint(synObj,"A",0); TestPrint t2 = new TestPrint(synObj,"B",1); TestPrint t3 = new TestPrint(synObj,"C",2); t1.start(); t2.start(); t3.start(); } }class TestPrint extends Thread{ private AtomicInteger syObj; private String name; private int flag; privateint count = 0; public TestPrint(AtomicInteger syObj, String name, int flag) { this.syObj = syObj; this.name = name; this.flag = flag; }@Override public void run() { while (true) { synchronized (syObj){ if (syObj.get() % 3 == flag){ syObj.set(syObj.get() + 1); System.out.println(name); count++; syObj.notifyAll(); if (count == 10){ break; } }else{ try { syObj.wait(); } catch (InterruptedException e) { e.printStackTrace(); } } } } } }

方法3:使用信号量

package com.ziyear.exam; import java.util.concurrent.Semaphore; /** * 使用信号量控制打印ABC */ public class PrintThread_ABC_10_3 { public static void main(String[] args) { PrintABCUsingSemaphore printABC = new PrintABCUsingSemaphore(); new Thread(new Runnable() { @Override public void run() { printABC.printA(); } }).start(); new Thread(new Runnable() { @Override public void run() { printABC.printB(); } }).start(); new Thread(new Runnable() { @Override public void run() { printABC.printC(); } }).start(); } }class PrintABCUsingSemaphore { /** * 第一个信号量初始化为1,其他初始化为0 3个信号量分别控制打印ABC * A有信号量,所以先打印A,打印完A后初始化第二个信号量B * B有信号量,所以打印B,打印完后初始化第三个信号量 * C有信号量,所以打印C,打印完后初始化第一个信号量 * ...... 每个线程各自在print方法中循环10次 * */ private Semaphore semaphoreA = new Semaphore(1); private Semaphore semaphoreB = new Semaphore(0); private Semaphore semaphoreC = new Semaphore(0); public void printA() { print("A", semaphoreA, semaphoreB); } public void printB() { print("B", semaphoreB, semaphoreC); } public void printC() { print("C", semaphoreC, semaphoreA); } private void print(String name, Semaphore currentSemaphore, Semaphore nextSemaphore) { for (int i = 0; i < 10; ) { try { currentSemaphore.acquire(); System.out.println(name); i++; nextSemaphore.release(); } catch (InterruptedException e) { e.printStackTrace(); } } } }