生产者消费者线程问题

package cn.star;

class Demok {
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(con);
t1.start();
t2.start();

}

}

class Resource {
private String name;
private int count = 1;
private boolean flag = false;

public synchronized void set(String name) {
if (flag)
try {
wait();
} catch (Exception e) {
}
this.name = name + "--" + count++;
System.out.println(Thread.currentThread().getName() + "...生产者.." + this.name);
flag = true;
this.notify();
}

public synchronized void out() {
if (!flag)
try {
wait();
} catch (Exception e) {
}
System.out.println(Thread.currentThread().getName() + "...消费者.." + 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();
}
}
}