java - 代码有什么问题吗？为什么线程不交错？

Question

class Producer implements Runnable{  //producer job here
    Vector<Integer> sQueue;
    public Producer(Vector<Integer> queue) {
        this.sQueue=queue;
    }
    public void run(){
        int i=0;
        try{
            synchronized(sQueue){
                for(i=0;i<30;i++){
                    if(sQueue.size()<15){
                        System.out.println("Producer producing the item:-"+i);
                        sQueue.add(i);
                        sQueue.notifyAll();
                    }
                    else
                    {   sQueue.notifyAll();
                        sQueue.wait();

                    }
                }
            }
        }
        catch(Exception e){
            e.printStackTrace();
        }
    }

}
class Consumer implements Runnable{
    Vector<Integer> sQueue;
    public Consumer(Vector<Integer> queue) {
        this.sQueue=queue;
    }
    public void run(){
        int i=0;
        try{
            synchronized(sQueue){
                while(true){
                    if(sQueue.size()>0){
                        System.out.println("Consumer is removing the item:-");
                        int item=sQueue.remove(0);
                        System.out.println(item);
                        sQueue.notifyAll();
                        Thread.sleep(1000);
                    }
                    else
                    {
                        sQueue.wait();
                    }
                }
            }
        }
        catch(Exception e){
            e.printStackTrace();
        }
    }
}
public class ProducerConsumerProblem {
    public static void main(String [] arg){
        Vector<Integer> sQueue;
        sQueue = new Vector<>(15);
        Producer p=new Producer(sQueue);
        Consumer c=new Consumer(sQueue);
        Thread producer=new Thread(p);
        Thread consumer=new Thread(c);
        producer.start();
        consumer.start();
    }
}

在上面的代码中，我试图借助java多线程来模拟生产者消费者问题。我使用 sQueue 作为共享队列，它是整数，我不知道出了什么问题，生产者线程和消费者线程没有交错，这是我机器上的输出

----------------------------output------------------------
Producer producing the item:-0
Producer producing the item:-1
Producer producing the item:-2
Producer producing the item:-3
Producer producing the item:-4
Producer producing the item:-5
Producer producing the item:-6
Producer producing the item:-7
Producer producing the item:-8
Producer producing the item:-9
Producer producing the item:-10
Producer producing the item:-11
Producer producing the item:-12
Producer producing the item:-13
Producer producing the item:-14
Consumer is removing the item:-
0
Consumer is removing the item:-
1
Consumer is removing the item:-
2
Consumer is removing the item:-
3
Consumer is removing the item:-
4
Consumer is removing the item:-
5
Consumer is removing the item:-
6
Consumer is removing the item:-
7
Consumer is removing the item:-
8
Consumer is removing the item:-
9
Consumer is removing the item:-
10
Consumer is removing the item:-
11
Consumer is removing the item:-
12
Consumer is removing the item:-
13
Consumer is removing the item:-
14
Producer producing the item:-16
Producer producing the item:-17
Producer producing the item:-18
Producer producing the item:-19
Producer producing the item:-20
Producer producing the item:-21
Producer producing the item:-22
Producer producing the item:-23
Producer producing the item:-24
Producer producing the item:-25
Producer producing the item:-26
Producer producing the item:-27
Producer producing the item:-28
Producer producing the item:-29
Consumer is removing the item:-
16
Consumer is removing the item:-
17
Consumer is removing the item:-
18
Consumer is removing the item:-
19
Consumer is removing the item:-
20
Consumer is removing the item:-
21
Consumer is removing the item:-
22
Consumer is removing the item:-
23
Consumer is removing the item:-
24
Consumer is removing the item:-
25
Consumer is removing the item:-
26
Consumer is removing the item:-
27
Consumer is removing the item:-
28
Consumer is removing the item:-
29

Answer 1

您的方法是同步的。当Producer启动时，它会获得队列上的锁，并且在完成之前不会释放它。当您的消费者启动时，它会等待直到可以获得锁。如果您希望它们交错，请不要同步...synchronized 关键字专门用于防止交错。