生产者/消费者多线程代码未按预期工作

Question

Sharedresource class

    class Sharedresource {
        private int contents;
        private boolean available = false;

        public synchronized int get() {
            while (available == false) {
                // System.out.println("sharedresorce,while(false)");
                try {
                    // /System.out.println("sharedresorce,while(false)object block");
                    wait();
                    // System.out.println("sharedresorce,while(false)object relise");
                } catch (Exception e) {
                    // System.out.println("Thread Interrupted");
                }
            }
            available = false;
            notify();
            return contents;
        }

        public synchronized void set(int value) {
            while (available == true) {
                try {
                    wait();
                } catch (Exception e) {
                    System.out.println("Thread Interrupted");
                }
            }
            contents = value;
            available = true;
            notify();
        }
    }

Produser class

    class Produser extends Thread {
        private Sharedresource resource;
        private int number;

        Produser(Sharedresource s, int number) {
            resource = s;
            this.number = number;
        }

        @Override
        public void run() {
            for (int i = 1; i <= 10; i++) {
                resource.set(i);
                System.out.println("produser#" + this.number + "set:" + i);
                // try{
                // sleep(2000);
                // }
                // catch (Exception e) {
                // System.out.println("tread intrupted");
                // }
            }
        }
    }

consumer class

    class Consumer extends Thread {
        private Sharedresource resource;
        private int number;

        public Consumer(Sharedresource s, int number) {
            resource = s;
            this.number = number;
        }

        int value = 0;

        @Override
        public void run() {
            for (int i = 1; i <= 10; i++) {
                value = resource.get();
                System.out.println("Consumer#" + this.number + "getvalue:" + value);

            }
        }
    }

MAIN CLASS

    public class SynchronizatonDemo121 {

        public static void main(String[] args) {
            Sharedresource r = new Sharedresource();
            Produser p = new Produser(r, 1);
            Consumer c = new Consumer(r, 1);
            p.start();
            c.start();

        }

    }

output-1

Consumer#1getvalue:1
produser#1set:1
produser#1set:2
Consumer#1getvalue:2
produser#1set:3
Consumer#1getvalue:3
produser#1set:4
Consumer#1getvalue:4
produser#1set:5
Consumer#1getvalue:5
produser#1set:6
Consumer#1getvalue:6
Consumer#1getvalue:7
produser#1set:7
produser#1set:8
produser#1set:9
Consumer#1getvalue:8
Consumer#1getvalue:9
produser#1set:10
Consumer#1getvalue:10                      

output-2

produser#1set:1
produser#1set:2
Consumer#1getvalue:1
Consumer#1getvalue:2
produser#1set:3
Consumer#1getvalue:3
produser#1set:4
Consumer#1getvalue:4
produser#1set:5
Consumer#1getvalue:5
produser#1set:6
Consumer#1getvalue:6
produser#1set:7
Consumer#1getvalue:7
produser#1set:8
Consumer#1getvalue:8
produser#1set:9
Consumer#1getvalue:9
produser#1set:10
Consumer#1getvalue:10

output-3

produser#1set:1
Consumer#1getvalue:1
Consumer#1getvalue:2
produser#1set:2
produser#1set:3
Consumer#1getvalue:3
produser#1set:4
Consumer#1getvalue:4
produser#1set:5
Consumer#1getvalue:5
produser#1set:6
Consumer#1getvalue:6
Consumer#1getvalue:7
produser#1set:7
produser#1set:8
Consumer#1getvalue:8
Consumer#1getvalue:9
produser#1set:9
produser#1set:10
Consumer#1getvalue:10

my threads are not working properly as per the producer and consumers behavior. I had attached my output over there for batter understanding so where is the problem in my code please verify me, thanks in advance

Answer 1

Your producer and consumer are producing and consuming the numbers in the expected order. However, the output is not synchronized, since you don't print it in synchronized methods, so you get a different order in each execution.

If you move your println statements to your synchronized get and set methods :

    public synchronized int get() {
        while (available == false) {
            // System.out.println("sharedresorce,while(false)");
            try {
                // /System.out.println("sharedresorce,while(false)object block");
                wait();
                // System.out.println("sharedresorce,while(false)object relise");
            } catch (Exception e) {
                // System.out.println("Thread Interrupted");
            }
        }
        available = false;
        notify();
        System.out.println("Consumer#"  + "getvalue:" + contents);
        return contents;
    }

    public synchronized void set(int value) {
        while (available == true) {
            try {
                wait();
            } catch (Exception e) {
                System.out.println("Thread Interrupted");
            }
        }
        contents = value;
        available = true;
        System.out.println("produser#" + "set:" + value);
        notify();
    }

You'll get the expected output :

produser#set:1
Consumer#getvalue:1
produser#set:2
Consumer#getvalue:2
produser#set:3
Consumer#getvalue:3
produser#set:4
Consumer#getvalue:4
produser#set:5
Consumer#getvalue:5
produser#set:6
Consumer#getvalue:6
produser#set:7
Consumer#getvalue:7
produser#set:8
Consumer#getvalue:8
produser#set:9
Consumer#getvalue:9
produser#set:10
Consumer#getvalue:10