private void getNextTetromino() {
        // Get next tetromino and generate new one
        Iterator<Tetromino> it = next.iterator();
        if (it.hasNext()) {
            tetromino = next.pop();
            next.add(bag.draw());
        } else {
            tetromino = bag.draw();
        }

        // Notify listeners that tetrominoes preview is updated.
        if (nextTetrominoesChangedListener != null)
            nextTetrominoesChangedListener.onNextTetrominoesChanged(next);

        // Lose player if game is lost.
		if (isLost()) {
            if (gameOverListener != null)
			    gameOverListener.onGameOver(false);
		}
	}