If cell contains formula, it evaluates the formula, and saves the result of the formula. The cell remains as a formula cell. If the cell does not contain formula, this method returns -1 and leaves the cell unchanged. Note that the type of the
formula result is returned, so you know what kind of cached formula result is also stored with the formula.
int evaluatedCellType = evaluator.evaluateFormulaCell(cell);
Be aware that your cell will hold both the formula, and the result. If you want the cell replaced with the result of the formula, use {@link #evaluateInCell(org.apache.poi.ss.usermodel.Cell)}
@param cell The cell to evaluate
@return -1 for non-formula cells, or the type of the
formula result