public boolean checkBulletCollision(Bullet bullet){
		
		int xIndex = (int) (bullet.getMovedX() / GRID_SIZE);
		int yIndex = (int) (bullet.getMovedY() / GRID_SIZE);
		
		if(xIndex < 0 || yIndex < 0)
			return true;
		
		if(grid.size() <= yIndex || grid.get(yIndex).size() <= xIndex)
			return true;
		
		if(grid.get(yIndex).get(xIndex) == GridType.Wall)
			return true;
		
		return false;
	}