/**
 * A Queue (of Object objects)
 *
 * This implementation uses contiguous memory
 *
 * @version 1.0
 * @author  Prof. David Bernstein, James Madison University
 */
public class Queue
{
    private int           back;
    private Object[]      contents;

    public static final int CAPACITY = 100;

    /**
     * Construct a new (empty) Queue
     */
    public Queue()
    {
	back  = -1;
	contents = new Object[CAPACITY];
    }



    /**
     * Pop an Object off of the front of this Queue
     *
     * @return  The Object at the front of this Queue
     */
    public Object pop()
    {
	int     i;
	Object  value;


	if (back != -1) 
        {
	    value = contents[0];

	    // Shuffle
	    for (i=0; i < back; i++)
	    {
		contents[i] = contents[i+1];
	    }

	    back  = back - 1;

	} 
	else
	{
	    value = null;
	}

	return value;
    }


    /**
     * Push an Object onto the back of this Queue
     *
     * @param last   The Object to push
     */
    public void push(Object last)
    {
	if (back < CAPACITY-1)
	{
	    back = back + 1;
	    contents[back] = last;
	}
    }
}