import java.util.concurrent.locks.*;class DuckMsg{    int size;//烤鸭的大小    String id;//烤鸭的厂家和标号    DuckMsg(){          }        DuckMsg(int size, String id){       this.size=size;       this.id=id;    }        public String toString(){       return id + " 大小为:"  + size;    }}class Duck{       private int count=0;//生产烤鸭的总数    private int putId=0, takeId=0;//分别表示存入的Id 和 取出烤鸭的Id        Lock lock = new ReentrantLock();    DuckMsg[] dk = new DuckMsg[100];//烤鸭的容器    Condition conProduce = lock.newCondition();    Condition conConsume = lock.newCondition();        public void put(int sz){        lock.lock();        try{            while(count==dk.length)//一直等到烤鸭全部生产完毕之后所有的生产线程都停止....               conProduce.await();            dk[putId++]=new DuckMsg(sz, Thread.currentThread().getName()+":"+(putId-1));            if(putId==dk.length)  putId=0;//啥意思呢？烤鸭的编号就是1到100， 如果过了100，那么再从编号1开始！            ++count;            conConsume.signal();        }catch(InterruptedException e){                }finally{            lock.unlock();        }            }        public void get(){       lock.lock();       try{           while(count==0)               conConsume.await();           System.out.println(dk[takeId++]);           System.out.println("......." + Thread.currentThread().getName());//打印消费的厂家           if(takeId==dk.length)  takeId=0;           --count;           conProduce.signal();        }catch(InterruptedException e){                    }finally{            lock.unlock();        }    }}class Producer implements Runnable{    Duck duck;    Producer(Duck duck){        this.duck=duck;    }    public void run(){       for(int i=1; ; ++i)        duck.put(i);    }}class Consumer implements Runnable{    Duck duck;    Consumer(Duck duck){        this.duck=duck;    }    public void run(){        while(true)          duck.get();    }}public class ProduceConsumeDemo{            public static void main(String[] args){          Duck duck=new Duck();          Thread t1 = new Thread(new Producer(duck), "生产厂家 1");          Thread t2 = new Thread(new Producer(duck), "生产厂家 2");          Thread t3 = new Thread(new Consumer(duck), "消费厂家 1");          Thread t4 = new Thread(new Consumer(duck), "消费厂家 2");                    t1.start();          t2.start();          t3.start();          t4.start();      }}