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## org.apache.poi.hssf.usermodel
Class HSSFFormulaEvaluator

    java.lang.Object
      org.apache.poi.hssf.usermodel.HSSFFormulaEvaluator

All Implemented Interfaces:
  FormulaEvaluator

    public class HSSFFormulaEvaluator

extends java.lang.Object
implements 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

Constructor Summary
`HSSFFormulaEvaluator(HSSFSheet sheet, HSSFWorkbook workbook)` Deprecated. (Sep 2008) HSSFSheet parameter is ignored
`HSSFFormulaEvaluator(HSSFWorkbook workbook)`
`HSSFFormulaEvaluator(HSSFWorkbook workbook, IStabilityClassifier stabilityClassifier)`

Method Summary
`void` | `clearAllCachedResultValues()` Should be called whenever there are major changes (e.g.
`static HSSFFormulaEvaluator` | `create(HSSFWorkbook workbook, IStabilityClassifier stabilityClassifier, UDFFinder udfFinder)`
`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.
`static void` | `evaluateAllFormulaCells(HSSFWorkbook wb)` Loops over all cells in all sheets of the supplied workbook.
`int` | `evaluateFormulaCell(Cell cell)` If cell contains formula, it evaluates the formula, and saves the result of the formula.
`HSSFCell` | `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` | `notifyDeleteCell(HSSFCell cell)` Should be called to tell the cell value cache that the specified cell has just been deleted.
`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` | `notifyUpdateCell(HSSFCell cell)` Should be called to tell the cell value cache that the specified (value or formula) cell has changed.
`void` | `setCurrentRow(HSSFRow row)` Deprecated. (Aug 2008) - not needed, since the current row can be derived from the cell
`static void` | `setupEnvironment(java.lang.String[] workbookNames, HSSFFormulaEvaluator[] evaluators)` Coordinates several formula evaluators together so that formulas that involve external references can be evaluated.

Methods inherited from class java.lang.Object
`equals, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

Constructor Detail

### HSSFFormulaEvaluator

    public HSSFFormulaEvaluator(HSSFSheet sheet,
                                HSSFWorkbook workbook)

  Deprecated. (Sep 2008) HSSFSheet parameter is ignored

### HSSFFormulaEvaluator

    public HSSFFormulaEvaluator(HSSFWorkbook workbook)

### HSSFFormulaEvaluator

    public HSSFFormulaEvaluator(HSSFWorkbook workbook,
                                IStabilityClassifier stabilityClassifier)

Parameters:
  `stabilityClassifier` - used to optimise caching performance. Pass `null` for the (conservative) assumption that any cell may have its definition changed after evaluation begins.

Method Detail

### create

    public static HSSFFormulaEvaluator create(HSSFWorkbook workbook,
                                              IStabilityClassifier stabilityClassifier,
                                              UDFFinder udfFinder)

  Parameters:
    `stabilityClassifier` - used to optimise caching performance. Pass `null` for the (conservative) assumption that any cell may have its definition changed after evaluation begins.
    `udfFinder` - pass `null` for default (AnalysisToolPak only)

### setupEnvironment

    public static void setupEnvironment(java.lang.String[] workbookNames,
                                        HSSFFormulaEvaluator[] evaluators)

  Coordinates several formula evaluators together so that formulas that involve external references can be evaluated.

  Parameters:
    `workbookNames` - the simple file names used to identify the workbooks in formulas with external links (for example "MyData.xls" as used in a formula "[MyData.xls]Sheet1!A1")
    `evaluators` - all evaluators for the full set of workbooks required by the formulas.

### setCurrentRow

    public void setCurrentRow(HSSFRow row)

  Deprecated. (Aug 2008) - not needed, since the current row can be derived from the cell

  Does nothing

### clearAllCachedResultValues

    public void clearAllCachedResultValues()

  Should be called whenever there are major changes (e.g. moving sheets) to input cells in the evaluated workbook. If performance is not critical, a single call to this method may be used instead of many specific calls to the notify~ methods. Failure to call this method after changing cell values will cause incorrect behaviour of the evaluate~ methods of this class

  Specified by:
    `clearAllCachedResultValues` in interface `FormulaEvaluator`

### notifyUpdateCell

    public void notifyUpdateCell(HSSFCell 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

### notifyUpdateCell

    public void notifyUpdateCell(Cell cell)

  Description copied from interface: `FormulaEvaluator`
  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

  Specified by:
    `notifyUpdateCell` in interface `FormulaEvaluator`

### notifyDeleteCell

    public void notifyDeleteCell(HSSFCell cell)

  Should be called to tell the cell value cache that the specified cell has just been deleted. Failure to call this method after changing cell values will cause incorrect behaviour of the evaluate~ methods of this class

### notifyDeleteCell

    public void notifyDeleteCell(Cell cell)

  Description copied from interface: `FormulaEvaluator`
  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

  Specified by:
    `notifyDeleteCell` in interface `FormulaEvaluator`

### notifySetFormula

    public 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

  Specified by:
    `notifySetFormula` in interface `FormulaEvaluator`

### evaluate

    public 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.

  Specified by:
    `evaluate` in interface `FormulaEvaluator`
  Parameters:
    `cell` - may be `null` signifying that the cell is not present (or blank)
  Returns:
    `null` if the supplied cell is `null` or blank

### evaluateFormulaCell

    public int 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. 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 `evaluateInCell(org.apache.poi.ss.usermodel.Cell)`

  Specified by:
    `evaluateFormulaCell` in interface `FormulaEvaluator`
  Parameters:
    `cell` - The cell to evaluate
  Returns:
    -1 for non-formula cells, or the type of the formula result

### evaluateInCell

    public HSSFCell 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 HSSFCell 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)`}

  Specified by:
    `evaluateInCell` in interface `FormulaEvaluator`

### evaluateAllFormulaCells

    public static void evaluateAllFormulaCells(HSSFWorkbook wb)

  Loops over all cells in all sheets of the supplied 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.

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