Bomb explosion on Bomberman game

Question

I'm writing a bomberman game in Java and I have already wrote the code for the map of the game (which contains tiles), the players (and their movement in the map) and now I am stuck in the code for the bomb explosion.

I have a Map class which contains a 2d array of Tiles, which can contain Players, Blocks and Bombs. The Player object have a method dropBomb who calls the method receiveBomb from the Map object (every Player has the reference of the Map object) with the position of the bomb and the bomb. When the Map method receiveBomb is called, the map put the bomb in the correct Tile. My problem is in the explosion of the bomb. Who should care about it? The bomb itself? If it is, should the bomb have the reference for the Tile that contains it? Until now my tile haven't need the Map reference.

One possibility that I thought is to have the Tile reference inside the Bomb object, so, when the bomb explodes (and the bomb knows when it should explode) it calls a method in the tile object for the explosion and the tile calls a method in the map. By the way, I don't know this is a good idea. What should I do?

public class Tile {

private boolean available; //if the tile is not occupied by a indestructible block or bomb
private List<Entity> entities; //you can have more than one player at a tile
public boolean receiveEntity(Entity entity) {
    boolean received = false;
    if (available) {
        this.entities.add(entity);
        received = true;
        if (entity instanceof Block || entity instanceof Bomb) {
            available = false;
        }
    }
    return received;        
}

public boolean removePlayer(Player player) {
    return entities.remove(player);
}
}

Player class:

public class Player implements Entity {

private Map gameMap;
private int posX;
private int posY;
private int explosionRange; //the explosion range for bombs
public Player(int posX, int posY, Map gameMap) {
    this.gameMap = gameMap;
    this.posX = posX;
    this.posY = posY;
    this.explosionRange = 1;
}

public void dropBomb() {
    gameMap.receiveBomb(new Bomb(explosionRange), posX, posY);
}
}

Map class:

public class Map {

private Grid<Tile> tileGrid;
private int width;
private int height;

public Map(int width, int height, BuildingStrategy buildingStrategy) {
    this.width = width;
    this.height = height;
    this.tileGrid = new Grid<Tile>(width, height);  
    buildingStrategy.buildMap(this);
}   
public void receiveBomb(Bomb bomb, int posX, int posY) {
    tileGrid.get(posX, posY).receiveEntity(bomb);
}
}

I have omitted the movement methods, because the movement is already fine.

Answer 1

I have always learned, and live by the rule "the table paints itself". The painter might choose the color and call the method, the floor might decide how the leaks and splatter is shown, but the table paints itself.

Back to your issue: the bomb explodes itself. This way you can have different effects of different bombs. The bomb has an effect on the tile, and the tile reacts to that.

Example: A bomb has a force and a type of explosion. The bomb, (occupying one and one tile only I think?) will 'give' it's effect to a tile.

Now it's the tile that deals with distributing this force. Lets say you have several kinds of bombs, one power (lets say a number between 1 and 10), and two type (lets say normal, incendiary, freeze).

Now your bomb explodes, and because your avatar is a level 5 fire-mage, your bombs are of power 4 and type incendiary. So you say to your tile: I explode with power 4 and I am setting you on fire!

Now the tile comes in to play. Any tile that gets 'touched' by the force of an explosion needs to call it's "Exploded" function to do stuff. If it is also on fire, there is more to do in the "onFire" function

What tiles are 'exploded' comes from force. Normal tiles with force 4 will give the expotion off to all squares within a range of 4, but if it is a special tile (it knows that from itself), like a mountain tile, it might not be able to advance with that force.

Tile 1 explodes with 4 and gives it to adjacent tiles with force 3. One of those tiles might be a wall, so doens't do anything further. Another is a normal tile, and explodes, and continues giving it forward with force 2, etc. If it is a 'water' tile, the explosion is pushed ofrward, but the fire isn't, etc

so:

• bomb explodes itself and gives calls the tiles explosion function
• tile is exploded and pushes explosion forward according to tile-type.
• subsequent tiles explode because of this.

In the end it might look like most of the work is done by the tiles, and this is probably even the case. but the first steps: the calculation of the force, type, and the first calls are from the bomb. The bomb explodes. And then the explosion has an effect on the tile. The tile handles that, and if needed propagates it.