使用Lock,Condition解决三个线程依次轮流打印出75个数

Love The Way You Lie 2022-07-11 13:01 196阅读 0赞

import java.util.concurrent.locks.Condition;
    import java.util.concurrent.locks.Lock;
    import java.util.concurrent.locks.ReentrantLock;
    
    public class CountTo_75 {
    
        public static void main(String[] args) {
            final Box box = new Box();
    
            new Thread(new Runnable() { // 线程1
                @Override
                public void run() {
                    for (int i = 1; i <= 5; i++) {
                        box.main_1();
                    }
                }
            },"Thread-1").start();
            new Thread(new Runnable() { // 线程2
                @Override
                public void run() {
                    for (int i = 1; i <= 5; i++) {
                        box.main_2();
                    }
                }
            },"Thread-2").start();
            new Thread(new Runnable() { // 线程3
                @Override
                public void run() {
                    for (int i = 1; i <= 5; i++) {
                        box.main_3();
                    }
                }
            },"Thread-3").start();
        }
    
        static class Box {
            Lock lock = new ReentrantLock();
            Condition condition_1 = lock.newCondition();
            Condition condition_2 = lock.newCondition();
            Condition condition_3 = lock.newCondition();
            private int flag = 1;
            public static int count = 0;   //用于计数的变量
    
            public void main_1() {
                lock.lock();
                try {
                    while(flag != 1){
                        try {
                            condition_1.await();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    for (int j = 0; j < 5; j++) {
                        count++;
                        System.out.println(Thread.currentThread().getName() +" "+ count);
                    }
                    flag = 2;
                    condition_2.signal();
                } finally {
                    lock.unlock();
                }
            }
    
            public void main_2() {
                lock.lock();
                try {
                    while(flag != 2){
                        try {
                            condition_2.await();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    for (int j = 0; j < 5; j++) {
                        count++;
                        System.out.println(Thread.currentThread().getName() +" " + count);
                    }
                    flag = 3;
                    condition_3.signal();
                } finally {
                    lock.unlock();
                }
            }
    
            public void main_3() {
                lock.lock();
                try {
                    while(flag != 3){
                        try {
                            condition_3.await();
                        } catch (InterruptedException e) {
                            e.printStackTrace();
                        }
                    }
                    for (int j = 0; j < 5; j++) {
                        count++;
                        System.out.println(Thread.currentThread().getName() + " " + count);
                    }
                    flag = 1;
                    condition_1.signal();
                } finally {
                    lock.unlock();
                }
            }
        }
    
    }

**结果：**  
Thread-1 1  
Thread-1 2  
Thread-1 3  
Thread-1 4  
Thread-1 5  
Thread-2 6  
Thread-2 7  
Thread-2 8  
Thread-2 9  
Thread-2 10  
Thread-3 11  
Thread-3 12  
Thread-3 13  
Thread-3 14  
Thread-3 15  
Thread-1 16  
Thread-1 17  
Thread-1 18  
Thread-1 19  
Thread-1 20  
Thread-2 21  
Thread-2 22  
Thread-2 23  
Thread-2 24  
Thread-2 25  
Thread-3 26  
Thread-3 27  
Thread-3 28  
Thread-3 29  
Thread-3 30  
Thread-1 31  
Thread-1 32  
Thread-1 33  
Thread-1 34  
Thread-1 35  
Thread-2 36  
Thread-2 37  
Thread-2 38  
Thread-2 39  
Thread-2 40  
Thread-3 41  
Thread-3 42  
Thread-3 43  
Thread-3 44  
Thread-3 45  
Thread-1 46  
Thread-1 47  
Thread-1 48  
Thread-1 49  
Thread-1 50  
Thread-2 51  
Thread-2 52  
Thread-2 53  
Thread-2 54  
Thread-2 55  
Thread-3 56  
Thread-3 57  
Thread-3 58  
Thread-3 59  
Thread-3 60  
Thread-1 61  
Thread-1 62  
Thread-1 63  
Thread-1 64  
Thread-1 65  
Thread-2 66  
Thread-2 67  
Thread-2 68  
Thread-2 69  
Thread-2 70  
Thread-3 71  
Thread-3 72  
Thread-3 73  
Thread-3 74  
Thread-3 75