Sample code for thread safe blocking queue in Java

ArrBlockingQueue.java

public class ArrBlockingQueue {

    final private Lock _lock = new ReentrantLock();
    final private Condition _notFull  = _lock.newCondition();
    final private Condition _notEmpty = _lock.newCondition();

    final private Object[] _items;
    private int _putptr, _takeptr, _count;

    public ArrBlockingQueue(final int size) {
      // Assuming size is valid here
      _items = new Object[size];
    }

    public void put(final Object x) throws InterruptedException {
      _lock.lock();
      try {
        while (_count == _items.length)
          _notFull.await();
        _items[_putptr] = x;
        if (++_putptr == _items.length) _putptr = 0;
        ++_count;
        _notEmpty.signalAll();
      } finally {
        _lock.unlock();
      }
    }

    public Object take() throws InterruptedException {
      _lock.lock();
      try {
        while (_count == 0)
          _notEmpty.await();
        Object x = _items[_takeptr];
        if (++_takeptr == _items.length) _takeptr = 0;
        --_count;
        _notFull.signalAll();
        return x;
      } finally {
        _lock.unlock();
      }
    }
}