package horstmann.ch09_queue3;
import java.util.ArrayList;
/**
    A first-in, first-out bounded collection of objects.
 */
public class BoundedQueue<E>
{
	/**
       Constructs an empty queue.
       @param capacity the maximum capacity of the queue
	 */
	public BoundedQueue(int capacity)
	{
		elements = new ArrayList<E>(capacity);
		head = 0;
		tail = 0;
		size = 0;
	}

	/**
       Removes the object at the head.
       @return the object that has been removed from the queue
	 */
	public synchronized E remove()
			throws InterruptedException
	{
		while (size == 0) wait();
		E r = elements.get(head);
		head++;
		size--;
		if (head == elements.size())
			head = 0;
		notifyAll();
		return r;
	}

	/**
       Appends an object at the tail.
       @param newValue the object to be appended
	 */
	public synchronized void add(E newValue)
			throws InterruptedException
	{
		while (size == elements.size()) wait();
		elements.set(tail,newValue);
		tail++;
		size++;
		if (tail == elements.size())
			tail = 0;
		notifyAll();
	}

	private ArrayList<E> elements;
	private int head;
	private int tail;
	private int size;
}