這個示例中BoundedBuffer是一個固定長度的集合，這個在其put操作時，如果發現長度已經達到最大長度，那么會等待notFull信號，如果得到notFull信號會像集合中添加元素，并發出notEmpty的信號，而在其take方法中如果發現集合長度為空，那么會等待notEmpty的信號，同時如果拿到一個元素，那么會發出notFull的信號。

package locks;




import java.util.Random;
import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;




public class AppOfficial {

    /**
     * BoundedBuffer 是一個定長100的集合，當集合中沒有元素時，take方法需要等待，直到有元素時才返回元素
     * 當其中的元素數達到最大值時，要等待直到元素被take之后才執行put的操作
     * @author yukaizhao
     *
     */
    static class BoundedBuffer {
        final Lock lock = new ReentrantLock();
        final Condition notFull = lock.newCondition();
        final Condition notEmpty = lock.newCondition();

        final Object[] items = new Object[100];
        int putptr, takeptr, count;

        public void put(Object x) throws InterruptedException {
            System .out.println("put wait lock");
            lock.lock();
            System.out.println("put get lock");
            try {
                while (count == items.length) {
                    System.out.println("buffer full, please wait");
                    notFull.await();
                }
                    
                items[putptr] = x;
                if (++putptr == items.length)
                    putptr = 0;
                ++count;
                notEmpty.signal();
            } finally {
                lock.unlock();
            }
        }




        public Object take() throws InterruptedException {
            System.out.println("take wait lock");
            lock.lock();
            System.out.println("take get lock");
            try {
                while (count == 0) {
                    System.out.println("no elements, please wait");
                    notEmpty.await();
                }
                Object x = items[takeptr];
                if (++takeptr == items.length)
                    takeptr = 0;
                --count;
                notFull.signal();
                return x;
            } finally {
                lock.unlock();
            }
        }
    }
    
    public static void main(String[] args) {
        final BoundedBuffer boundedBuffer = new BoundedBuffer();
        
        Thread t1 = new Thread(new Runnable() {
            @Override
            public void run() {
                System.out.println("t1 run");
                for (int i=0;i<1000;i++) {
                    try {
                        System.out.println("putting..");
                        boundedBuffer.put(Integer.valueOf(i));
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
            
        }) ;
        
        Thread t2 = new Thread(new Runnable() {
            @Override
            public void run() {
                for (int i=0;i<1000;i++) {
                    try {
                        Object val = boundedBuffer.take();
                        System.out.println(val);
                    } catch (InterruptedException e) {
                        e.printStackTrace();
                    }
                }
            }
            
        }) ;
        
        t1.start();
        t2.start();
    }
}

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