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package horstmann.ch09_queue1;
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
       <p><b>Precondition:</b> !isEmpty()</p>
   */
  public E remove()
  {
    if (debug) System.out.print("removeFirst");
    E r = elements.get(head);
    if (debug) System.out.print(".");
    head++;
    if (debug) System.out.print(".");
    size--;
    if (head == elements.size())
    {
      if (debug) System.out.print(".");
      head = 0;
    }
    if (debug)
      System.out.println("head=" + head + ",tail=" + tail
          + ",size=" + size);
    return r;
  }

  /**
       Appends an object at the tail.
       @param newValue the object to be appended
       <p><b>Precondition:</b> !isFull();</p>
   */
  public void add(E newValue)
  {
    if (debug) System.out.print("add");
    elements.set(tail,newValue);
    if (debug) System.out.print(".");
    tail++;
    if (debug) System.out.print(".");
    size++;
    if (tail == elements.size())
    {
      if (debug) System.out.print(".");
      tail = 0;
    }
    if (debug)
      System.out.println("head=" + head + ",tail=" + tail
          + ",size=" + size);
  }

  public boolean isFull()
  {
    return size == elements.size();
  }

  public boolean isEmpty()
  {
    return size == 0;
  }

  public void setDebug(boolean newValue)
  {
    debug = newValue;
  }

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