生产者消费者--多个线程出现的问题

柔情只为你懂 2022-08-09 09:44 159阅读 0赞

package comm;
    
    public class ProducerConsumerDemo { 
    
        public static void main(String[] args) {
            Resource r = new Resource();
            Producer pro = new Producer(r);
            Consumer con = new Consumer(r);
    
            Thread t1 = new Thread(pro);
            Thread t2 = new Thread(pro);
            Thread t3 = new Thread(con);
            Thread t4 = new Thread(con);
            t1.start();
            t2.start();
            t3.start();
            t4.start();
        }
    }
    
    class Resource { 
        private String name;
        private int count = 1;
        private boolean flag = false;
    
        public synchronized void set(String name) {
            if (flag)
                try {
                    this.wait();
                } catch (InterruptedException e) {
                }
            this.name = name + "==" + (count++);
            System.out.println(Thread.currentThread().getName() + "==producer=="
                    + this.name);
            flag = true;
            this.notify();
        }
    
        public synchronized void out() {
            if (!flag)
                try {
                    this.wait();
                } catch (InterruptedException e) {
                }
            System.out.println(Thread.currentThread().getName() + "====consumer===="
                    + this.name);
            flag = false;
            this.notify();
        }
    }
    
    class Producer implements Runnable { 
        private Resource res;
    
        Producer(Resource res) {
            this.res = res;
        }
    
        public void run() {
            while (true)
                res.set("+商品+");
        }
    }
    
    class Consumer implements Runnable { 
        private Resource res;
    
        Consumer(Resource res) {
            this.res = res;
        }
    
        public void run() {
            while (true)
                res.out();
        }
    }

输出中出现一个商品被消费2次的情况出现

Thread-0==producer==+商品+==19112
    Thread-3====consumer====+商品+==19112
    Thread-2====consumer====+商品+==19112