顺序打印（有三个线程，线程名称分别为：a，b，c...）

缺乏、安全感 2023-09-27 10:31 103阅读 0赞

**目录**

1.顺序打印-普通版

2. 顺序打印-进阶版

--------------------

## 1.顺序打印-普通版 ##

> 有三个线程，线程名称分别为：a，b，c。
> 
> 每个线程打印自己的名称。
> 
> 需要让他们同时启动，并按 c，b，a的顺序打印

public class Demo08 {
        public static void main(String[] args) {
            Thread c = new Thread(() -> {
                System.out.println(Thread.currentThread().getName()+" ");
            },"c");
    
            Thread b = new Thread(() -> {
                try {
                    c.join();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(Thread.currentThread().getName()+" ");
            },"b");
    
            Thread a = new Thread(() -> {
                try {
                    b.join();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
                System.out.println(Thread.currentThread().getName());
            },"a");
            a.start();
            b.start();
            c.start();
        }
    }

## 2. 顺序打印-进阶版 ##

> 有三个线程，分别只能打印A，B和C
> 
> 要求按顺序打印ABC，打印10次
> 
> 输出示例：
> 
> ABC
> 
> ABC
> 
> ABC
> 
> ABC
> 
> ABC
> 
> ABC
> 
> ABC
> 
> ABC
> 
> ABC
> 
> ABC

public class Demo01 {
        // 计数器
        private static volatile int COUNTER = 0;
        // 定义一个锁对象
        private static Object lock = new Object();
    
        public static void main(String[] args) {
            // 创建三个线程，并指定线程名，每个线程名分别用A,B,C表示
            Thread t1 = new Thread(() -> {
                // 循环10次
                for (int i = 0; i < 10; i++) {
                    // 执行的代码加锁
                    synchronized (lock) {
                        // 每次唤醒后都重新判断是否满足条件
                        // 每条线程判断的条件不一样，注意线程t1,t2
                        while (COUNTER % 3 != 0) {
                            try {
                                // 不满足输出条件时，主动等待并释放锁
                                lock.wait();
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                        // 满足输出条件，打印线程名，每条线程打印的内容不同
                        System.out.print(Thread.currentThread().getName());
                        // 累加计数
                        COUNTER++;
                        // 唤醒其他线程
                        lock.notifyAll();
                    }
                }
            }, "A");
    
            Thread t2 = new Thread(() -> {
                for (int i = 0; i < 10; i++) {
                    synchronized (lock) {
                        while (COUNTER % 3 != 1) {
                            try {
                                lock.wait();
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
                        System.out.print(Thread.currentThread().getName());
                        COUNTER++;
                        lock.notifyAll();
                    }
                }
            }, "B");
    
            Thread t3 = new Thread(() -> {
                for (int i = 0; i < 10; i++) {
                    synchronized (lock) {
                        while (COUNTER % 3 != 2) {
                            try {
                                lock.wait();
                            } catch (InterruptedException e) {
                                e.printStackTrace();
                            }
                        }
    
                        // 换行打印
                        System.out.println(Thread.currentThread().getName());
                        COUNTER++;
                        lock.notifyAll();
                    }
                }
            }, "C");
    
            // 启动线程
            t1.start();
            t2.start();
            t3.start();
        }
    }

方法二，也可以使用三个锁，分别控制

public class Demo04 {
        private static Object locker1 = new Object();
        private static Object locker2 = new Object();
        private static Object locker3 = new Object();
    
        public static void main(String[] args) throws InterruptedException {
            Thread t1 = new Thread(() -> {
                try {
                    for (int i = 0; i < 10; i++) {
                        synchronized (locker1) {
                            locker1.wait();
                        }
                        System.out.print("A");
                        synchronized (locker2) {
                            locker2.notify();
                        }
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            });
    
            Thread t2 = new Thread(() -> {
                try {
                    for (int i = 0; i < 10; i++) {
                        synchronized (locker2) {
                            locker2.wait();
                        }
                        System.out.print("B");
                        synchronized (locker3) {
                            locker3.notify();
                        }
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            });
    
            Thread t3 = new Thread(() -> {
                try {
                    for (int i = 0; i < 10; i++) {
                        synchronized (locker3) {
                            locker3.wait();
                        }
                        System.out.println("C");
                        synchronized (locker1) {
                            locker1.notify();
                        }
                    }
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            });
            t1.start();
            t2.start();
            t3.start();
    
            Thread.sleep(1000);
    
            synchronized (locker1) {
                locker1.notify();
            }
        }
    }