Java - 2d Array Tile Map Collision

Question

How would I go about making certain tiles in my array collide with my player? Like say I want every number 2 in the array to collide. I am reading my array from a txt file if that matters and I am using the slick2d library.

Here is my code if needed.

public class Tiles {

Image[] tiles = new Image[3];

int[][] map = new int[500][500];

Image grass, dirt, mound;

SpriteSheet tileSheet;

int tileWidth = 32;
int tileHeight = 32;

public void init() throws IOException, SlickException {
    tileSheet = new SpriteSheet("assets/tiles.png", tileWidth, tileHeight);

    grass = tileSheet.getSprite(0, 0);
    dirt = tileSheet.getSprite(7, 7);
    mound = tileSheet.getSprite(2, 6);
    tiles[0] = grass;
    tiles[1] = dirt; 
    tiles[2] = mound;

    int x=0, y=0;
BufferedReader in = new BufferedReader(new FileReader("assets/map.txt"));
String line;
while ((line = in.readLine()) != null) {
        String[] values = line.split(",");
    for (String str : values) {
            int str_int = Integer.parseInt(str);
            map[x][y]=str_int;
            //System.out.print(map[x][y] + " ");
            y=y+1;
        }
//System.out.println("");
x=x+1;
    y = 0;
}
    in.close();
}

public void update() {

}

public void render(GameContainer gc) {
    for(int x = 0; x < 50; x++) {
        for(int y = 0; y < 50; y ++) {
            int textureIndex = map[y][x];
            Image texture = tiles[textureIndex];
            texture.draw(x*tileWidth,y*tileHeight);
        }
    }
}

}

Edit - Solved

public boolean collision() {
    playerRect = new Rectangle(x,y, playerWidth, playerHeight);

    for(int i = 0; i < tiles.map.length; i++) {
        for(int j = 0; j < tiles.map.length; j++) {
            if(tiles.map[j][i] == 2 || tiles.map[j][i] == 3) {
                tileRect = new Rectangle(i*tiles.tileWidth, j*tiles.tileHeight, tiles.tileWidth,tiles.tileHeight);
                rect.add(tileRect);
            }
        }
    }  
    for(Rectangle collision : rect) {
        if(collision.intersects(playerRect)) { 
            return true;
        }
    }
    return false;
}

Answer 1

You have a tile grid, and you have tile dimensions. That's a good start.

You're missing a key piece, though. You're trying to do collision between the player and the tiles (based purely on player location). This is a bit flawed. Instead, you should think about this problem as collision between player geometry and tile geometry.

To keep it simple, you can represent your player and tiles as rectangles. The player rectangle can be computed given the x location, y location, width, and height (if your player yet have height and width, you should add them).

Tile geometries (rectangles) can be computed in a similar manner, which should be fairly obvious:

• x location = tile grid x index * tileWidth
• y location = tile grid y index * tileHeight
• width = tileWidth
• height = tileHeight

Now do your collision checks. Hint: Have a look java.awt.Rectangle or java.awt.geom.Rectangle2D. These will help you.