public void makeMove(){

        ArrayList<Position> freeChecks = new ArrayList<Position>();

        /* get Free Checks */
        for (int i = 0; i < board.getSize(); i++) {
            for (int j = 0; j < board.getSize(); j++) {
                if (board.getBoardField()[i][j] == board.getDefaultSymbol()) {
                    freeChecks.add(new Position(i, j));
                }
            }
        }

        /* Attack or Defend*/
        int i = 0;
        while (!successfulAttack(freeChecks, i) && !successfulDefend(freeChecks, i)) {
            i++;
        }

    }