public class TileId
{
    public static final char WALL = '#';
    public static final char SPACE = ' ';
    public static final char PASSAGE = '.';

    private TileId ()  // prevent instantiation!
    {
    }
}
public class TileId
{
    public static final char WALL = '#';
    public static final char SPACE = ' ';
    public static final char PASSAGE = '.';
    public static final char DOOR = '%';

    private TileId ()  // prevent instantiation!
    {
    }
}
Update TileId.java