Formula Support | ![]() |
Introduction
This document describes the current state of formula support in POI. The information in this document currently applies to the 2.0 version of POI. Since this area is a work in progress, this document will be updated with new features as and when they are added.
The basics
In org.apache.poi.hssf.usermodel.HSSFCell setCellFormula("formulaString") is used to add a formula to sheet and getCellFormula() is used to retrieve the string representation of a formula.
We aim to support the complete excel grammer for formulas. Thus, the string that you pass in to the setCellFormula call should be what you expect to type into excel. Also, note that you should NOT add a "=" to the front of the string.
Supported Features
- Cell References
- String, integer and floating point literals
- Area references
- Relative or absolute references
- Arithmetic and logical operators
- Sheet or Macro Functions (inlcuding logical functions)
- Sheet References
- Formual return values (number or string)
Partially supported
- Formula tokens in Excel are stored in one of three possible classes : Reference, Value and Array. Based on the location of a token, its class can change in complicated and undocumented ways. While we have support for most cases, we are not sure if we have covered all bases (since there is no documentation for this area.) We would therefore like you to report any occurence of #VALUE! in a cell upon opening a POI generated workbook in excel. (Check that typing the formula into Excel directly gives a valid result.)
Not yet supported
- Array formulas
- Unary Operators
- 3D References
- Error Values (cells containing #REF's or #VALUE's)
- Everything else :)
Internals
Formulas in Excel are stored as sequences of tokens in Reverse Polish Notation order. The open office XLS spec is the best documentation you will find for the format.
The tokens used by excel are modelled as individual *Ptg classes in the org.apache.poi.hssf.record.formula package.
The task of parsing a formula string into an array of RPN ordered tokens is done by the org.apache.poi.hssf.record.formula.FormulaParser class. This class implements a hand written recursive descent parser.
Check out the javadocs for details.