关于两个生产者两个消费者的运行结果——求解释 - 黑马程序员技术交流社区

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public synchronized void produce(String name) {
if(flag) {//问题出现在这里：if判断标记，只有一次，会导致不该运行的线程运行了。出现了数据错误的情况。while判断标记，解决了线程获取执行权后，是否要运行！
try {
wait();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
this.name = name + "---" + no++;
System.out.println(Thread.currentThread().getName() +
"---生产者: " + this.name);
flag = true;
notify();//同时这里改成notifyAll();不然出现死锁情况
}

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class Resource
{
private String name;
private int count = 1;
private boolean flag = false;
public synchronized void set(String name)
{
while(flag)
try{this.wait();}catch(InterruptedException e){}
this.name = name + count;
count++;
System.out.println(Thread.currentThread().getName()+"...生产者..."+this.name);
flag = true;
notifyAll();
}
public synchronized void out()// t3
{
while(!flag)
try{this.wait();}catch(InterruptedException e){}
System.out.println(Thread.currentThread().getName()+"...消费者........"+this.name);
flag = false;
notifyAll();
}
}
class Producer implements Runnable
{
private Resource r;
Producer(Resource r)
{
this.r = r;
}
public void run()
{
while(true)
{
r.set("商品");
}
}
}
class Consumer implements Runnable
{
private Resource r;
Consumer(Resource r)
{
this.r = r;
}
public void run()
{
while(true)
{
r.out();
}
}
}
class ProducerConsumerDemo
{
public static void main(String[] args)
{
Resource r = new Resource();
Producer pro = new Producer(r);
Consumer con = new Consumer(r);
Thread t0 = new Thread(pro);
Thread t1 = new Thread(pro);
Thread t2 = new Thread(con);
Thread t3 = new Thread(con);
t0.start();
t1.start();
t2.start();
t3.start();
}

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