I have a array right now, 

```
    static int[][] map = new int[WIDTH][HEIGHT];

```

This code places tiles on the map:

```
for (int y = 18; y < HEIGHT; y++) {
        for (int x = 0; x < WIDTH; x++) {
            map[x][y] = STONE;
        }

    }

    for (int y = 18; y < 19; y++) {
        for (int x = 0; x < WIDTH; x++) {
            map[x][y] = GRASS;
        }

    }

    for (int y = 19; y < 20; y++) {
        for (int x = 0; x < WIDTH; x++) {
            map[x][y] = DIRT;
        }

    }

```

And here is how I render them:

```
for (int x = 0; x < WIDTH; x++) {
        for (int y = 0; y < HEIGHT; y++) {
            switch (map[x][y]) {
            case CLEAR:
                air.draw(x * TILE_SIZE, y * TILE_SIZE, TILE_SIZE, TILE_SIZE);
                break;
            case STONE:
                stone.draw(x * TILE_SIZE, y * TILE_SIZE, TILE_SIZE, TILE_SIZE);
                break;
            case GRASS:
                grass.draw(x * TILE_SIZE, y * TILE_SIZE, TILE_SIZE, TILE_SIZE);
                break;
            case DIRT:
                dirt.draw(x * TILE_SIZE, y * TILE_SIZE, TILE_SIZE, TILE_SIZE);
                break;
            }
        }
    }

```

How can I convert this code to replace the array map with a 2 dimensional arraylist so I can remove these tiles like minecraft?