UnboundedGrid.java

/* 
 * AP(r) Computer Science GridWorld Case Study:
 * Copyright(c) 2002-2006 College Entrance Examination Board 
 * (http://www.collegeboard.com).
 *
 * This code is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * @author Alyce Brady
 * @author APCS Development Committee
 * @author Cay Horstmann
 */

package info.gridworld.grid;

import java.util.ArrayList;

import java.util.*;

/**
 * An <code>UnboundedGrid</code> is a rectangular grid with an unbounded number of rows and
 * columns. <br />
 * The implementation of this class is testable on the AP CS AB exam.
 */
public class UnboundedGrid<E> extends AbstractGrid<E>
{
    private Map<Location, E> occupantMap;

    /**
     * Constructs an empty unbounded grid.
     */
    public UnboundedGrid()
    {
        occupantMap = new HashMap<Location, E>();
    }

    public int getNumRows()
    {
        return -1;
    }

    public int getNumCols()
    {
        return -1;
    }

    public boolean isValid(Location loc)
    {
        return true;
    }

    public ArrayList<Location> getOccupiedLocations()
    {
        ArrayList<Location> a = new ArrayList<Location>();
        for (Location loc : occupantMap.keySet())
            a.add(loc);
        return a;
    }

    public E get(Location loc)
    {
        if (loc == null)
            throw new NullPointerException("loc == null");
        return occupantMap.get(loc);
    }

    public E put(Location loc, E obj)
    {
        if (loc == null)
            throw new NullPointerException("loc == null");
        if (obj == null)
            throw new NullPointerException("obj == null");
        return occupantMap.put(loc, obj);
    }

    public E remove(Location loc)
    {
        if (loc == null)
            throw new NullPointerException("loc == null");
        return occupantMap.remove(loc);
    }
}