AbstractGrid

package feAttempt;

/*
 * AP(r) Computer Science GridWorld Case Study:
 * Copyright(c) 2005-2006 Cay S. Horstmann (http://horstmann.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 Cay Horstmann
 */

import java.util.ArrayList;

/**
 * <code>AbstractGrid</code> contains the methods that are common to grid
 * implementations. <br />
 * The implementation of this class is testable on the AP CS AB exam.
 */
public abstract class AbstractGrid<E> implements Grid<E>
{
  public ArrayList<E> getNeighbors(Location loc)
  {
    ArrayList<E> neighbors = new ArrayList<E>();
    for (Location neighborLoc : getOccupiedAdjacentLocations(loc))
      neighbors.add(get(neighborLoc));
    return neighbors;
  }

  public ArrayList<Location> getValidAdjacentLocations(Location loc)
  {
    ArrayList<Location> locs = new ArrayList<Location>();

    int d = Location.NORTH;
    for (int i = 0; i < Location.FULL_CIRCLE / Location.HALF_RIGHT; i++)
    {
      Location neighborLoc = loc.getAdjacentLocation(d);
      if (isValid(neighborLoc))
        locs.add(neighborLoc);
      d = d + Location.HALF_RIGHT;
    }
    return locs;
  }

  public ArrayList<Location> getEmptyAdjacentLocations(Location loc)
  {
    ArrayList<Location> locs = new ArrayList<Location>();
    for (Location neighborLoc : getValidAdjacentLocations(loc))
    {
      if (get(neighborLoc) == null)
        locs.add(neighborLoc);
    }
    return locs;
  }

  public ArrayList<Location> getOccupiedAdjacentLocations(Location loc)
  {
    ArrayList<Location> locs = new ArrayList<Location>();
    for (Location neighborLoc : getValidAdjacentLocations(loc))
    {
      if (get(neighborLoc) != null)
        locs.add(neighborLoc);
    }
    return locs;
  }

  /**
   * Creates a string that describes this grid.
   * @return a string with descriptions of all objects in this grid (not
   * necessarily in any particular order), in the format {loc=obj, loc=obj,
   * ...}
   */
  public String toString()
  {
    String s = "{";
    for (Location loc : getOccupiedLocations())
    {
      if (s.length() > 1)
        s += ", ";
      s += loc + "=" + get(loc);
    }
    return s + "}";
  }
}