FormulaEvaluator (POI API Documentation)

All Known Implementing Classes:

BaseFormulaEvaluator, BaseXSSFFormulaEvaluator, HSSFFormulaEvaluator, SXSSFFormulaEvaluator, XSSFFormulaEvaluator
```
public interface FormulaEvaluator
```
Evaluates formula cells.
For performance reasons, this class keeps a cache of all previously calculated intermediate cell values. Be sure to call clearAllCachedResultValues() if any workbook cells are changed between calls to evaluate~ methods on this class.

Author:

Amol S. Deshmukh < amolweb at ya hoo dot com >, Josh Micich

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`clearAllCachedResultValues()` Should be called whenever there are changes to input cells in the evaluated workbook.
`CellValue`	`evaluate(Cell cell)` If cell contains a formula, the formula is evaluated and returned, else the CellValue simply copies the appropriate cell value from the cell and also its cell type.
`void`	`evaluateAll()` Loops over all cells in all sheets of the associated workbook.
`CellType`	`evaluateFormulaCell(Cell cell)` If cell contains formula, it evaluates the formula, and saves the result of the formula.
`Cell`	`evaluateInCell(Cell cell)` If cell contains formula, it evaluates the formula, and puts the formula result back into the cell, in place of the old formula.
`void`	`notifyDeleteCell(Cell cell)` Should be called to tell the cell value cache that the specified cell has just become a formula cell, or the formula text has changed
`void`	`notifySetFormula(Cell cell)` Should be called to tell the cell value cache that the specified (value or formula) cell has changed.
`void`	`notifyUpdateCell(Cell cell)` Should be called to tell the cell value cache that the specified (value or formula) cell has changed.
`void`	`setDebugEvaluationOutputForNextEval(boolean value)` Perform detailed output of formula evaluation for next evaluation only? Is for developer use only (also developers using POI for their XLS files).
`void`	`setIgnoreMissingWorkbooks(boolean ignore)` Whether to ignore missing references to external workbooks and use cached formula results in the main workbook instead.
`void`	`setupReferencedWorkbooks(java.util.Map<java.lang.String,FormulaEvaluator> workbooks)` Sets up the Formula Evaluator to be able to reference and resolve links to other workbooks, eg [Test.xls]Sheet1!A1.

- Method Detail
  - clearAllCachedResultValues
```
void clearAllCachedResultValues()
```
    Should be called whenever there are changes to input cells in the evaluated workbook. Failure to call this method after changing cell values will cause incorrect behaviour of the evaluate~ methods of this class
  - notifySetFormula
```
void notifySetFormula(Cell cell)
```
    Should be called to tell the cell value cache that the specified (value or formula) cell has changed. Failure to call this method after changing cell values will cause incorrect behaviour of the evaluate~ methods of this class
  - notifyDeleteCell
```
void notifyDeleteCell(Cell cell)
```
    Should be called to tell the cell value cache that the specified cell has just become a formula cell, or the formula text has changed
  - notifyUpdateCell
```
void notifyUpdateCell(Cell cell)
```
    Should be called to tell the cell value cache that the specified (value or formula) cell has changed. Failure to call this method after changing cell values will cause incorrect behaviour of the evaluate~ methods of this class
  - evaluateAll
```
void evaluateAll()
```
    Loops over all cells in all sheets of the associated workbook. For cells that contain formulas, their formulas are evaluated, and the results are saved. These cells remain as formula cells. For cells that do not contain formulas, no changes are made. This is a helpful wrapper around looping over all cells, and calling evaluateFormulaCell on each one.
  - evaluate
```
CellValue evaluate(Cell cell)
```
    If cell contains a formula, the formula is evaluated and returned, else the CellValue simply copies the appropriate cell value from the cell and also its cell type. This method should be preferred over evaluateInCell() when the call should not modify the contents of the original cell.
    
    Parameters:
    
    cell - The Cell to evaluate
  - evaluateFormulaCell
```
CellType evaluateFormulaCell(Cell cell)
```
    If cell contains formula, it evaluates the formula, and saves the result of the formula. The cell remains as a formula cell. Else if cell does not contain formula, this method leaves the cell unchanged. Note that the type of the formula result is returned, so you know what kind of value 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 evaluateInCell(Cell)
    Parameters:
    
    cell - The cell to evaluate
    
    Returns:
    
    The type of the formula result, i.e. -1 if the cell is not a formula, or one of CellType.NUMERIC, CellType.STRING, CellType.BOOLEAN, CellType.ERROR Note: the cell's type remains as CellType.FORMULA however.
  - evaluateInCell
```
Cell evaluateInCell(Cell cell)
```
    If cell contains formula, it evaluates the formula, and puts the formula result back into the cell, in place of the old formula. Else if cell does not contain formula, this method leaves the cell unchanged. Note that the same instance of Cell is returned to allow chained calls like:
```
 int evaluatedCellType = evaluator.evaluateInCell(cell).getCellType();
 
```
    Be aware that your cell value will be changed to hold the result of the formula. If you simply want the formula value computed for you, use evaluateFormulaCell(Cell)
    Parameters:
    
    cell - The Cell to evaluate and modify.
  - setupReferencedWorkbooks
```
void setupReferencedWorkbooks(java.util.Map<java.lang.String,FormulaEvaluator> workbooks)
```
    Sets up the Formula Evaluator to be able to reference and resolve links to other workbooks, eg [Test.xls]Sheet1!A1.
    For a workbook referenced as [Test.xls]Sheet1!A1, you should supply a map containing the key Test.xls (no square brackets), and an open FormulaEvaluator onto that Workbook.
    
    Parameters:
    
    workbooks - Map of workbook names (no square brackets) to an evaluator on that workbook
  - setIgnoreMissingWorkbooks
```
void setIgnoreMissingWorkbooks(boolean ignore)
```
    Whether to ignore missing references to external workbooks and use cached formula results in the main workbook instead.
    In some cases external workbooks referenced by formulas in the main workbook are not available. With this method you can control how POI handles such missing references:
    - by default ignoreMissingWorkbooks=false and POI throws CollaboratingWorkbooksEnvironment.WorkbookNotFoundException if an external reference cannot be resolved
    - if ignoreMissingWorkbooks=true then POI uses cached formula result that already exists in the main workbook
    Parameters:
    
    ignore - whether to ignore missing references to external workbooks
  - setDebugEvaluationOutputForNextEval
```
void setDebugEvaluationOutputForNextEval(boolean value)
```
    Perform detailed output of formula evaluation for next evaluation only? Is for developer use only (also developers using POI for their XLS files). Log-Level WARN is for basic info, INFO for detailed information. These quite high levels are used because you have to explicitly enable this specific logging.
    
    Parameters:
    
    value - whether to perform detailed output

Interface FormulaEvaluator

Method Summary

Method Detail

clearAllCachedResultValues

notifySetFormula

notifyDeleteCell

notifyUpdateCell

evaluateAll

evaluate

evaluateFormulaCell

evaluateInCell

setupReferencedWorkbooks

setIgnoreMissingWorkbooks

setDebugEvaluationOutputForNextEval