多线程同步问题

Question

一个简单的程序:生产者和消费者同步问题
ProductorDemo类:
import java.util.Stack;
public class ProductorDemo implements Runnable
{

Stack<Integer> stack=new Stack<Integer>();
public void run()
{
synchronized (stack)
        {

for(int i=0;i<10;i++)
{
                                int intrand=(int)(Math.random()*10)+1;
stack.push(new Integer(intrand));
System.out.println("push:"+(int)intrand);
} 
        }

}
}
ConsumerDemo 类:
public class ConsumerDemo implements Runnable
{
ProductorDemo productorDemo=new ProductorDemo();
public void run()
{
try
        {
        Thread.sleep(1000);
        } catch (InterruptedException e)
        {
        // TODO: handle exception
         e.printStackTrace();
        }
        synchronized(productorDemo.stack) //这样行么?如果不行,能否解释下为什么.        {
try
            {
if(productorDemo.stack.isEmpty())
{
System.out.println("There are no goods for consuming!");
Thread.sleep(1000);
}
productorDemo.stack.pop();
            } catch (InterruptedException e)
            {
            // TODO: handle exception
             e.printStackTrace();
            }
catch(Exception e)
{
e.printStackTrace();
}
//this.consume();

        }
}
}
测试类:
public class ProduceAndConsumeTest 
{ /**
 * @param args
 */
Thread productor=new Thread(new ProductorDemo());
Thread consumer=new Thread (new ConsumerDemo());
public ProduceAndConsumeTest()
{
productor.start();
consumer.start();
}
public static void main(String[] args)
{

// TODO Auto-generated method stub

new ProduceAndConsumeTest(); }}
调试结果说是java.util.EmptyStackException,哪里出错了?

Answer 1

第一个类里面已经对stack做了同步限制了，这里应该不用再写这条语句了——synchronized(productorDemo.stack)

Answer 2

如果不加这条语句,能实现同步么?
我是想在对临界资源stack进行进栈和出栈操作时互斥.

Answer 3

出现java.util.EmptyStackException这个的原因是，你的生产者和消费者没有共享一个stack
代码我给你贴出来，改好了

Answer 4

import java.util.Stack;
public class ProduceAndConsumeTest 
{    /**
     * @param args
     */
    Thread productor=new Thread(new ProductorDemo());
    Thread consumer=new Thread (new ConsumerDemo());
    public ProduceAndConsumeTest()
    {
        productor.start();
        consumer.start();
    }
    public static void main(String[] args)
    {
        
        // TODO Auto-generated method stub
        
        new ProduceAndConsumeTest();    }}class ProductorDemo implements Runnable
{
    
    static Stack<Integer> stack=new Stack<Integer>();
    public void run()
    {
        synchronized (stack)
        {
            
            for(int i=0;i<10;i++)
            {
                int intrand=(int)(Math.random()*10)+1;
                stack.push(new Integer(intrand));
                System.out.println("push:"+(int)intrand);
            } 
        }
        
    }
}
class ConsumerDemo implements Runnable
{
    //ProductorDemo productorDemo=new ProductorDemo();
    public void run()
    {
        try
        {
            Thread.sleep(1000);
        } catch (InterruptedException e)
        {
            // TODO: handle exception
            e.printStackTrace();
        }
        synchronized(ProductorDemo.stack) {
                try
                {
                   for(int i=0;i<10;i++){
                    if(ProductorDemo.stack.isEmpty())
                    {
                        System.out.println("There are no goods for consuming!");
                        Thread.sleep(1000);
                    }
                    Integer j=(Integer)ProductorDemo.stack.pop();
                    System.out.println("pop:"+j);
                  }
                } catch (InterruptedException e){
                    // TODO: handle exception
                    e.printStackTrace();
                }
                catch(Exception e)
                {
                    e.printStackTrace();
                }
            //this.consume();         
        }
    }
}

Answer 5

我在LINUX下编译，就有一个错误。ProduceAndConsumeTest.java:57: <identifier> expected
    Stack<Integer> stack=new Stack<Integer>();
         ^
1 error