BlockingQueue: as the name implies, first it is a queue, and supports blocking mechanism, blocking putting and getting data. We need to implement two methods, put and take, under LinkedBlockingQueue

put(anObject): add an object to BlockingQueue. If BlockingQueue has no space, the thread calling this method will be blocked until there is space in BlockingQueue.

Take: take away the first object in BlockingQueue. If BlockingQueue is empty, block entering the waiting state until new data is added to BlockingQueue.

public class MyQueue {

    // 1 A set of mounting elements is required
    private LinkedList<Object> list = new LinkedList<Object>();

    // 2 A counter is required
    private AtomicInteger count = new AtomicInteger(0);

    // 3 Upper and lower limits need to be established
    private final int minSize = 0;

    private final int maxSize;

    // 4 Construction method
    public MyQueue(int size) {
        this.maxSize = size;
    }

    // 5 Initializing an object for locking
    private final Object lock = new Object();

    // put(anObject):
    // hold anObject Add to BlockingQueue in,If BlockQueue no space,The thread calling this method is blocked until BlockingQueue There's room to move on.
    public void put(Object obj) {
        synchronized (lock) {
            while (count.get() == this.maxSize) {
                try {
                    lock.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            // 1 Adding elements
            list.add(obj);
            // 2 Counter accumulation
            count.incrementAndGet();
            // 3 Notify another thread (wake up)
            lock.notify();
            System.out.println("The newly added element is:" + obj);
        }
    }

    // take:
    // Take away BlockingQueue Top of the list,if BlockingQueue Empty,Block to wait until BlockingQueue New data is added.
    public Object take() {
        Object ret = null;
        synchronized (lock) {
            while (count.get() == this.minSize) {
                try {
                    lock.wait();
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }
            // 1 Remove element
            ret = list.removeFirst();
            // 2 Counter decrement
            count.decrementAndGet();
            // 3 Wake up another thread
            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("Length of current container:" + 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("Removed elements are:" + o1);
                Object o2 = mq.take();
                System.out.println("Removed elements are:" + o2);
            }
        }, "t2");

        try {
            TimeUnit.SECONDS.sleep(2);
        } catch (InterruptedException e) {
            e.printStackTrace();
        }

        t2.start();
    }
}