private void generateMines() {
        for (int index = 0; index<mineCount; index++){
            int randomRow = new Random().nextInt(getRowCount());
            int randomColumn = new Random().nextInt(getColumnCount());
            if (getTile(randomRow, randomColumn)!=null){
                --index;
            } else {
                tiles[randomRow][randomColumn] = new Mine();
            }
        }
    }