import java.util.LinkedList;
import java.util.concurrent.TimeUnit;
import java.util.concurrent.atomic.AtomicInteger;

public class MyQueue {
    
    private LinkedList<Object> list = new LinkedList<Object>();
    
    //原子計數(shù)器
    private AtomicInteger count = new AtomicInteger(0);
    
    //需要制定上限和下限
    private final int minSize = 0;
    
    private final int maxSize;
    
    
    //4構造方法
    public MyQueue(int size) {
        this.maxSize = size;
    }
    
    //5初始化一個對象 用于加鎖 
    private final Object lock  = new Object();
    
    //put(anObject):把anObject加到BlockingQueue里，如果blockqueue沒有空間，
    //則調用方法的線程被阻斷，直到blockingqueue里面有空間再繼續(xù)。
    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.計數(shù)器累加
            count.incrementAndGet();
            
            //3.通知另外一個線程
            lock.notify();
            System.out.println("新加入的元素為:"+obj);
        }
    }
    
    /**
     * take: 取走blockingqueue里排在首位的對象，若blockingqueue為空
     * 阻斷進入等待狀態(tài)直到blockqueue有新的數(shù)據(jù)加入
     * @return
     */
    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 計數(shù)器遞減
                count.decrementAndGet();
                //3 喚醒另外一個線程
                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("當前容器的長度:"+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("移除的元素為:"+o1);
                Object o2 = mq.take();
                System.out.println("移除的元素為:"+o2);
            }
        },"t2");
        
        
        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }
        
        t2.start();
    }
    
    
    
    
    
}