moparisthebest/poi
1
0
Fork 0
Code Issues Pull Requests Releases 1 Wiki Activity

Update formula eval docs for xssf support

Browse Source 
git-svn-id: https://svn.apache.org/repos/asf/poi/branches/ooxml@642637 13f79535-47bb-0310-9956-ffa450edef68
This commit is contained in:
Nick Burch 2008-03-29 22:50:44 +00:00
parent fb674709b7
commit 7ceef61ca6
1 changed files with 58 additions and 56 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

114
src/documentation/content/xdocs/spreadsheet/eval.xml
View File

@ -48,57 +48,59 @@
functions in Excel. The framework however makes is easy to add
implementation of new functions. See the <link href="eval-devguide.html"> Formula
evaluation development guide</link> for details. </p>
<p> Both HSSFWorkbook and XSSFWorkbook are supported, so you can
evaluate formulas on both .xls and .xlsx files.</p>
<p> Note that user-defined functions are not supported, and is not likely to done
any time soon... at least, not till there is a VB implementation in Java!
</p>
</section>
<section><title>User API How-TO</title>
<p>The following code demonstrates how to use the HSSFFormulaEvaluator
<p>The following code demonstrates how to use the FormulaEvaluator
in the context of other POI excel reading code.
</p>
<p>There are several ways in which you can use the HSSFFormulaEvalutator API.</p>
<p>There are several ways in which you can use the FormulaEvalutator API.</p>
<anchor id="Evaluate"/>
<section><title>Using HSSFFormulaEvaluator.<strong>evaluate</strong>(HSSFCell cell)</title>
<section><title>Using FormulaEvaluator.<strong>evaluate</strong>(Cell cell)</title>
<p>This evaluates a given cell, and returns the new value,
without affecting the cell</p>
<source>
FileInputStream fis = new FileInputStream("c:/temp/test.xls");
HSSFWorkbook wb = new HSSFWorkbook(fis);
HSSFSheet sheet = wb.getSheetAt(0);
HSSFFormulaEvaluator evaluator = new HSSFFormulaEvaluator(sheet, wb);
Workbook wb = new HSSFWorkbook(fis);
Sheet sheet = wb.getSheetAt(0);
FormulaEvaluator evaluator = new FormulaEvaluator(sheet, wb);
// suppose your formula is in B3
CellReference cellReference = new CellReference("B3");
HSSFRow row = sheet.getRow(cellReference.getRow());
HSSFCell cell = row.getCell(cellReference.getCol());
Row row = sheet.getRow(cellReference.getRow());
Cell cell = row.getCell(cellReference.getCol());
evaluator.setCurrentRow(row);
HSSFFormulaEvaluator.CellValue cellValue = evaluator.evaluate(cell);
FormulaEvaluator.CellValue cellValue = evaluator.evaluate(cell);
switch (cellValue.getCellType()) {
case HSSFCell.CELL_TYPE_BOOLEAN:
case Cell.CELL_TYPE_BOOLEAN:
System.out.println(cellValue.getBooleanValue());
break;
case HSSFCell.CELL_TYPE_NUMERIC:
case Cell.CELL_TYPE_NUMERIC:
System.out.println(cellValue.getNumberValue());
break;
case HSSFCell.CELL_TYPE_STRING:
case Cell.CELL_TYPE_STRING:
System.out.println(cellValue.getStringValue());
break;
case HSSFCell.CELL_TYPE_BLANK:
case Cell.CELL_TYPE_BLANK:
break;
case HSSFCell.CELL_TYPE_ERROR:
case Cell.CELL_TYPE_ERROR:
break;
// CELL_TYPE_FORMULA will never happen
case HSSFCell.CELL_TYPE_FORMULA:
case Cell.CELL_TYPE_FORMULA:
break;
}
</source>
<p>Thus using the retrieved value (of type
HSSFFormulaEvaluator.CellValue - a nested class) returned
by HSSFFormulaEvaluator is similar to using a HSSFCell object
FormulaEvaluator.CellValue - a nested class) returned
by FormulaEvaluator is similar to using a Cell object
containing the value of the formula evaluation. CellValue is
a simple value object and does not maintain reference
to the original cell.
@ -106,46 +108,46 @@ switch (cellValue.getCellType()) {
</section>
<anchor id="EvaluateFormulaCell"/>
<section><title>Using HSSFFormulaEvaluator.<strong>evaluateFormulaCell</strong>(HSSFCell cell)</title>
<p><strong>evaluateFormulaCell</strong>(HSSFCell cell)
<section><title>Using FormulaEvaluator.<strong>evaluateFormulaCell</strong>(Cell cell)</title>
<p><strong>evaluateFormulaCell</strong>(Cell cell)
will check to see if the supplied cell is a formula cell.
If it isn't, then no changes will be made to it. If it is,
then the formula is evaluated. The value for the formula
is saved alongside it, to be displayed in excel. The
formula remains in the cell, just with a new value</p>
<p>The return of the function is the type of the
formula result, such as HSSFCell.CELL_TYPE_BOOLEAN</p>
formula result, such as Cell.CELL_TYPE_BOOLEAN</p>
<source>
FileInputStream fis = new FileInputStream("/somepath/test.xls");
HSSFWorkbook wb = new HSSFWorkbook(fis);
HSSFSheet sheet = wb.getSheetAt(0);
HSSFFormulaEvaluator evaluator = new HSSFFormulaEvaluator(sheet, wb);
Workbook wb = new HSSFWorkbook(fis);
Sheet sheet = wb.getSheetAt(0);
FormulaEvaluator evaluator = new FormulaEvaluator(sheet, wb);
// suppose your formula is in B3
CellReference cellReference = new CellReference("B3");
HSSFRow row = sheet.getRow(cellReference.getRow());
HSSFCell cell = row.getCell(cellReference.getCol());
Row row = sheet.getRow(cellReference.getRow());
Cell cell = row.getCell(cellReference.getCol());
evaluator.setCurrentRow(row);
if (cell!=null) {
switch (<strong>evaluator.evaluateFormulaCell</strong>(cell)) {
case HSSFCell.CELL_TYPE_BOOLEAN:
case Cell.CELL_TYPE_BOOLEAN:
System.out.println(cell.getBooleanCellValue());
break;
case HSSFCell.CELL_TYPE_NUMERIC:
case Cell.CELL_TYPE_NUMERIC:
System.out.println(cell.getNumberCellValue());
break;
case HSSFCell.CELL_TYPE_STRING:
case Cell.CELL_TYPE_STRING:
System.out.println(cell.getStringCellValue());
break;
case HSSFCell.CELL_TYPE_BLANK:
case Cell.CELL_TYPE_BLANK:
break;
case HSSFCell.CELL_TYPE_ERROR:
case Cell.CELL_TYPE_ERROR:
System.out.println(cell.getErrorCellValue());
break;
// CELL_TYPE_FORMULA will never occur
case HSSFCell.CELL_TYPE_FORMULA:
case Cell.CELL_TYPE_FORMULA:
break;
}
}
@ -153,43 +155,43 @@ if (cell!=null) {
</section>
<anchor id="EvaluateInCell"/>
<section><title>Using HSSFFormulaEvaluator.<strong>evaluateInCell</strong>(HSSFCell cell)</title>
<p><strong>evaluateInCell</strong>(HSSFCell cell) will check to
<section><title>Using FormulaEvaluator.<strong>evaluateInCell</strong>(Cell cell)</title>
<p><strong>evaluateInCell</strong>(Cell cell) will check to
see if the supplied cell is a formula cell. If it isn't,
then no changes will be made to it. If it is, then the
formula is evaluated, and the new value saved into the cell,
in place of the old formula.</p>
<source>
FileInputStream fis = new FileInputStream("/somepath/test.xls");
HSSFWorkbook wb = new HSSFWorkbook(fis);
HSSFSheet sheet = wb.getSheetAt(0);
HSSFFormulaEvaluator evaluator = new HSSFFormulaEvaluator(sheet, wb);
Workbook wb = new HSSFWorkbook(fis);
Sheet sheet = wb.getSheetAt(0);
FormulaEvaluator evaluator = new FormulaEvaluator(sheet, wb);
// suppose your formula is in B3
CellReference cellReference = new CellReference("B3");
HSSFRow row = sheet.getRow(cellReference.getRow());
HSSFCell cell = row.getCell(cellReference.getCol());
Row row = sheet.getRow(cellReference.getRow());
Cell cell = row.getCell(cellReference.getCol());
evaluator.setCurrentRow(row);
if (cell!=null) {
switch (<strong>evaluator.evaluateInCell</strong>(cell).getCellType()) {
case HSSFCell.CELL_TYPE_BOOLEAN:
case Cell.CELL_TYPE_BOOLEAN:
System.out.println(cell.getBooleanCellValue());
break;
case HSSFCell.CELL_TYPE_NUMERIC:
case Cell.CELL_TYPE_NUMERIC:
System.out.println(cell.getNumberCellValue());
break;
case HSSFCell.CELL_TYPE_STRING:
case Cell.CELL_TYPE_STRING:
System.out.println(cell.getStringCellValue());
break;
case HSSFCell.CELL_TYPE_BLANK:
case Cell.CELL_TYPE_BLANK:
break;
case HSSFCell.CELL_TYPE_ERROR:
case Cell.CELL_TYPE_ERROR:
System.out.println(cell.getErrorCellValue());
break;
// CELL_TYPE_FORMULA will never occur
case HSSFCell.CELL_TYPE_FORMULA:
case Cell.CELL_TYPE_FORMULA:
break;
}
}
@ -200,18 +202,18 @@ if (cell!=null) {
<section><title>Re-calculating all formulas in a Workbook</title>
<source>
FileInputStream fis = new FileInputStream("/somepath/test.xls");
HSSFWorkbook wb = new HSSFWorkbook(fis);
Workbook wb = new HSSFWorkbook(fis);
for(int sheetNum = 0; sheetNum &lt; wb.getNumberOfSheets(); sheetNum++) {
HSSFSheet sheet = wb.getSheetAt(sheetNum);
HSSFFormulaEvaluator evaluator = new HSSFFormulaEvaluator(sheet, wb);
Sheet sheet = wb.getSheetAt(sheetNum);
FormulaEvaluator evaluator = new FormulaEvaluator(sheet, wb);
for(Iterator rit = sheet.rowIterator(); rit.hasNext();) {
HSSFRow r = (HSSFRow)rit.next();
Row r = (Row)rit.next();
evaluator.setCurrentRow(r);
for(Iterator cit = r.cellIterator(); cit.hasNext();) {
HSSFCell c = (HSSFCell)cit.next();
if(c.getCellType() == HSSFCell.CELL_TYPE_FORMULA) {
Cell c = (Cell)cit.next();
if(c.getCellType() == Cell.CELL_TYPE_FORMULA) {
evaluator.evaluateFormulaCell(c);
}
}
@ -225,22 +227,22 @@ wb.write(new FileOutputStream("/somepath/changed.xls"));
<anchor id="Performance"/>
<section><title>Performance Notes</title>
<ul>
<li>Generally you should have to create only one HSSFFormulaEvaluator
<li>Generally you should have to create only one FormulaEvaluator
instance per sheet, but there really is no overhead in creating
multiple HSSFFormulaEvaluators per sheet other than that of the
HSSFFormulaEvaluator object creation.
multiple FormulaEvaluators per sheet other than that of the
FormulaEvaluator object creation.
</li>
<li>Also note that HSSFFormulaEvaluator maintains a reference to
<li>Also note that FormulaEvaluator maintains a reference to
the sheet and workbook, so ensure that the evaluator instance
is available for garbage collection when you are done with it
(in other words don't maintain long lived reference to
HSSFFormulaEvaluator if you don't really need to - unless
FormulaEvaluator if you don't really need to - unless
all references to the sheet and workbook are removed, these
don't get garbage collected and continue to occupy potentially
large amounts of memory).
</li>
<li>CellValue instances however do not maintain reference to the
HSSFCell or the sheet or workbook, so these can be long-lived
Cell or the sheet or workbook, so these can be long-lived
objects without any adverse effect on performance.
</li>
</ul>