import java.util.LinkedList;

   import java.util.concurrent.TimeUnit;

   import java.util.concurrent.atomic.AtomicInteger;

   public class MyQueue {

       //1 需要一个承装元素的集合

       private LinkedList<Object> list = new LinkedList<Object>();

       //2 需要一个计数器

       private AtomicInteger count = new AtomicInteger(0);

       //3 需要制定上限和下限

       private final int minSize = 0;

       private final int maxSize ;

       //4 构造方法

       public MyQueue(int size){

         this.maxSize = size;

       }

       //5 初始化一个对象 用于加锁

       private final Object lock = new Object();

       //put(anObject): 把anObject加到BlockingQueue里,如果BlockQueue没有空间,则调用此方法的线程被阻断，直到BlockingQueue里面有空间再继续.

       public void put(Object obj){

         synchronized (lock) {

           while(count.get() == this.maxSize){

             try {

               lock.wait();

             } catch (InterruptedException e) {

               e.printStackTrace();

             }

           }

           //1 加入元素

           list.add(obj);

           //2 计数器累加

           count.incrementAndGet();

           //3 通知另外一个线程（唤醒）

           lock.notify();

           System.out.println("新加入的元素为:" + obj);

         }

       }

       //take: 取走BlockingQueue里排在首位的对象,若BlockingQueue为空,阻断进入等待状态直到BlockingQueue有新的数据被加入.

       public Object take(){

         Object ret = null;

         synchronized (lock) {

           while(count.get() == this.minSize){

             try {

               lock.wait();

             } catch (InterruptedException e) {

               e.printStackTrace();

             }

           }

           //1 做移除元素操作

           ret = list.removeFirst();

           //2 计数器递减

           count.decrementAndGet();

           //3 唤醒另外一个线程

           lock.notify();

         }

         return ret;

       }

       public int getSize(){

         return this.count.get();

       }

       public static void main(String[] args) {

         final MyQueue mq = new MyQueue(5);

         mq.put("a");

         mq.put("b");

         mq.put("c");

         mq.put("d");

         mq.put("e");

         System.out.println("当前容器的长度:" + mq.getSize());

         Thread t1 = new Thread(new Runnable() {

           @Override

           public void run() {

             mq.put("f");

             mq.put("g");

           }

         },"t1");

         t1.start();

         Thread t2 = new Thread(new Runnable() {

           @Override

           public void run() {

             Object o1 = mq.take();

             System.out.println("移除的元素为:" + o1);

             Object o2 = mq.take();

             System.out.println("移除的元素为:" + o2);

           }

         },"t2");

         try {

           TimeUnit.SECONDS.sleep(2);

         } catch (InterruptedException e) {

           e.printStackTrace();

         }

         t2.start();

       }

   }