Develop Reference

copy cells between Excel workbooks with Apache POI

I'm trying to copy from cells from one workbook to another with the latest version of Apache POI (4.1.2).
If both workbooks are .xlsx files, everything works fine. But if the source workbook is an (old) .xls file and the destination workbook is an .xlsx file, the following code fails
// Copy style from old cell and apply to new cell
CellStyle newCellStyle = targetWorkbook.createCellStyle();
newCellStyle.cloneStyleFrom(sourceCell.getCellStyle());
targetCell.setCellStyle(newCellStyle);
The exception that's thrown is:
java.lang.IllegalArgumentException: Can only clone from one XSSFCellStyle to another, not between HSSFCellStyle and XSSFCellStyle
If we can't use cloneStyleFrom when the files (or Workbook objects) are of different types, how can we convert a HSSFCellStyle object to a XSSFCellStyle?

The answer to your question "How can we convert a HSSFCellStyle object to a XSSFCellStyle?" is: We can't do that using apache poi 4.1.2. This simply is not supported as clearly stated in CellStyle.cloneStyleFrom: "However, both of the CellStyles will need to be of the same type (HSSFCellStyle or XSSFCellStyle)."
The other question is: Should we at all convert one cell style into another? Or what use cases are there for CellStyle.cloneStyleFrom at all? In my opinion there are none. There are Excel limitations for the count of unique cell formats/cell styles. See Excel specifications and limits. So we should not create a single cell style for each single cell because then those limitations will be reached very fast. So instead of cloning cell styles we should get the style properties from source style style1 and then using CellUtil.setCellStyleProperties to set those style properties to the other cell in question. This method attempts to find an existing CellStyle that matches the cell's current style plus styles properties in properties. A new style only is created if the workbook does not contain a matching style.
Since your question title is "Copy cells between Excel workbooks with Apache POI", I have created a working draft of how I woud do this.
The following code first gets a existent Workbook.xls as HSSFWorkbook wb1 and creates a new XSSFWorkbook wb2. Then it loops over all cells of the first sheet of wb1 and tries copying those cells into the first sheet of wb2. To do so there is a method copyCells(Cell cell1, Cell cell2) which uses copyStyles(Cell cell1, Cell cell2). The latter gets the style properties from source style style1 got from cell1 and then uses CellUtil.setCellStyleProperties to set those style properties to cell2. For copying fonts copyFont(Font font1, Workbook wb2) is used. This tries creating new fonts in wb2 only if such a font is not already present in that workbook. This is necessary because there also is a limit of unique font types per workbook in Excel.
Working example:
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.apache.poi.ss.usermodel.CellType;
import org.apache.poi.ss.util.CellUtil;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.*;
class ExcelCopyCells {
static Font copyFont(Font font1, Workbook wb2) {
boolean isBold = font1.getBold();
short color = font1.getColor();
short fontHeight = font1.getFontHeight();
String fontName = font1.getFontName();
boolean isItalic = font1.getItalic();
boolean isStrikeout = font1.getStrikeout();
short typeOffset = font1.getTypeOffset();
byte underline = font1.getUnderline();
Font font2 = wb2.findFont(isBold, color, fontHeight, fontName, isItalic, isStrikeout, typeOffset, underline);
if (font2 == null) {
font2 = wb2.createFont();
font2.setBold(isBold);
font2.setColor(color);
font2.setFontHeight(fontHeight);
font2.setFontName(fontName);
font2.setItalic(isItalic);
font2.setStrikeout(isStrikeout);
font2.setTypeOffset(typeOffset);
font2.setUnderline(underline);
}
return font2;
}
static void copyStyles(Cell cell1, Cell cell2) {
CellStyle style1 = cell1.getCellStyle();
Map<String, Object> properties = new HashMap<String, Object>();
//CellUtil.DATA_FORMAT
short dataFormat1 = style1.getDataFormat();
if (BuiltinFormats.getBuiltinFormat(dataFormat1) == null) {
String formatString1 = style1.getDataFormatString();
DataFormat format2 = cell2.getSheet().getWorkbook().createDataFormat();
dataFormat1 = format2.getFormat(formatString1);
}
properties.put(CellUtil.DATA_FORMAT, dataFormat1);
//CellUtil.FILL_PATTERN
//CellUtil.FILL_FOREGROUND_COLOR
FillPatternType fillPattern = style1.getFillPattern();
short fillForegroundColor = style1.getFillForegroundColor(); //gets only indexed colors, no custom HSSF or XSSF colors
properties.put(CellUtil.FILL_PATTERN, fillPattern);
properties.put(CellUtil.FILL_FOREGROUND_COLOR, fillForegroundColor);
//CellUtil.FONT
Font font1 = cell1.getSheet().getWorkbook().getFontAt(style1.getFontIndexAsInt());
Font font2 = copyFont(font1, cell2.getSheet().getWorkbook());
properties.put(CellUtil.FONT, font2.getIndexAsInt());
//BORDERS
BorderStyle borderStyle = null;
short borderColor = -1;
//CellUtil.BORDER_LEFT
//CellUtil.LEFT_BORDER_COLOR
borderStyle = style1.getBorderLeft();
properties.put(CellUtil.BORDER_LEFT, borderStyle);
borderColor = style1.getLeftBorderColor();
properties.put(CellUtil.LEFT_BORDER_COLOR, borderColor);
//CellUtil.BORDER_RIGHT
//CellUtil.RIGHT_BORDER_COLOR
borderStyle = style1.getBorderRight();
properties.put(CellUtil.BORDER_RIGHT, borderStyle);
borderColor = style1.getRightBorderColor();
properties.put(CellUtil.RIGHT_BORDER_COLOR, borderColor);
//CellUtil.BORDER_TOP
//CellUtil.TOP_BORDER_COLOR
borderStyle = style1.getBorderTop();
properties.put(CellUtil.BORDER_TOP, borderStyle);
borderColor = style1.getTopBorderColor();
properties.put(CellUtil.TOP_BORDER_COLOR, borderColor);
//CellUtil.BORDER_BOTTOM
//CellUtil.BOTTOM_BORDER_COLOR
borderStyle = style1.getBorderBottom();
properties.put(CellUtil.BORDER_BOTTOM, borderStyle);
borderColor = style1.getBottomBorderColor();
properties.put(CellUtil.BOTTOM_BORDER_COLOR, borderColor);
CellUtil.setCellStyleProperties(cell2, properties);
}
static void copyCells(Cell cell1, Cell cell2) {
switch (cell1.getCellType()) {
case STRING:
/*
//TODO: copy HSSFRichTextString to XSSFRichTextString
RichTextString rtString1 = cell1.getRichStringCellValue();
cell2.setCellValue(rtString1); // this fails if cell2 is XSSF and rtString1 is HSSF
*/
String string1 = cell1.getStringCellValue();
cell2.setCellValue(string1);
break;
case NUMERIC:
if (DateUtil.isCellDateFormatted(cell1)) {
Date date1 = cell1.getDateCellValue();
cell2.setCellValue(date1);
} else {
double cellValue1 = cell1.getNumericCellValue();
cell2.setCellValue(cellValue1);
}
break;
case FORMULA:
String formula1 = cell1.getCellFormula();
cell2.setCellFormula(formula1);
break;
//case : //TODO: further cell types
}
copyStyles(cell1, cell2);
}
public static void main(String[] args) throws Exception {
Workbook wb1 = WorkbookFactory.create(new FileInputStream("Workbook.xls"));
Workbook wb2 = new XSSFWorkbook();
Sheet sheet1 = wb1.getSheetAt(0);
Sheet sheet2 = wb2.createSheet();
Set<Integer> columns = new HashSet<Integer>();
Row row2 = null;
Cell cell2 = null;
for (Row row1 : sheet1) {
row2 = sheet2.createRow(row1.getRowNum());
for (Cell cell1 : row1) {
columns.add(cell1.getColumnIndex());
cell2 = row2.createCell(cell1.getColumnIndex());
copyCells(cell1, cell2);
}
}
wb1.close();
for (Integer column : columns) {
sheet2.autoSizeColumn(column);
}
FileOutputStream out = new FileOutputStream("Workbook.xlsx");
wb2.write(out);
out.close();
wb2.close();
}
}
If Workbook.xls looks like this:
then the resulting Workbook.xlsx looks like this:
Note: This is a working draft and needs to be completed. See TODO comments in the code. RichTextString cell values needs to be considered. Further cell types needs to be considered.
Method copyStyles only provides copying data format, fill pattern and fill foreground color (only for indexed colors), font and borders. Further cell style properties needs to be considered.

Java Excel automation cell background color repeating setFillForegroundColor

Hey all I have the code below that changes the background of a cell to either RED or GREEN. It seems that when I comment out the GREEN else code that my excel sheet has all red for each cell box in row 1. Likewise, if I do the opposite and comment out RED and un-comment GREEN then all the cells in row 1 are green.
I'm not understanding what in the code below is making it color all the cells the same color even though the first 2 cells should be RED while all the others should be GREEN. I already checked my logic and its going to the first IF 2 times and then the rest is going to the else so that's correct.
My code:
static CellStyle headerCellStyle = workbook.createCellStyle();
for (int i = 0; i < arr.length; i++) {
Row row = sheet.createRow(rowNum1++);
HSSFWorkbook hwb = new HSSFWorkbook();
HSSFPalette palette = hwb.getCustomPalette();
Cell cell = row.createCell(colNum);
headerCellStyle.setWrapText(true);
headerCellStyle.setAlignment(HorizontalAlignment.LEFT);
headerCellStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);
headerCellStyle.setAlignment(HorizontalAlignment.JUSTIFY);
headerCellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
if (arr[i].contains("*")) {
//RED
headerCellStyle.setFillForegroundColor(IndexedColors.RED.getIndex());
cell.setCellValue(arr[i].replace(" " + (i + 1) + ".xml*", ""));
} else {
//GREEN
headerCellStyle.setFillForegroundColor(IndexedColors.GREEN.getIndex());
cell.setCellValue(arr[i].replace(" " + (i + 1) + ".xml", ""));
}
row.getCell(0).setCellStyle(headerCellStyle);
row.setHeightInPoints(20);
}
I'm sure I am just looking over something quite obvious but at this time I'm not able to find what that may be.
Any help would be great!
Note: Also posted to the following forums:
coderanch.com
codeguru

The cell fills are stored in the cell styles and those are stored on workbook level. So never do creating the cell styles in same loop which sets cell values into the sheet.
If two different cell fills (one having red and one having green solid pattern) are needed, then also two cell styles are needed. Those needs to be created on workbook level first and then be set as cell style within the loop which sets the cell values.
Your code is not complete, so I can only guess, what exactly you are trying to achieve.
I hope the following minimal but complete example will help you:
import java.io.FileOutputStream;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
public class CreateExcelCellStyleRedAndGreen {
public static void main(String[] args) throws Exception {
//Workbook workbook = new XSSFWorkbook();
Workbook workbook = new HSSFWorkbook();
CellStyle headerCellStyleRed = workbook.createCellStyle();
CellStyle headerCellStyleGreen = workbook.createCellStyle();
headerCellStyleRed.setWrapText(true);
headerCellStyleRed.setFillPattern(FillPatternType.SOLID_FOREGROUND);
headerCellStyleRed.setAlignment(HorizontalAlignment.JUSTIFY);
headerCellStyleRed.setVerticalAlignment(VerticalAlignment.CENTER);
headerCellStyleGreen.cloneStyleFrom(headerCellStyleRed);
headerCellStyleRed.setFillForegroundColor(IndexedColors.RED.getIndex());
headerCellStyleGreen.setFillForegroundColor(IndexedColors.GREEN.getIndex());
String[] arr = new String[] {
"A Name of File.xml",
"B Name of File.xml*",
"C Name of File.xml",
"D Name of File.xml",
"E Name of File.xml*",
"F Name of File.xml"
};
int rowNum=1;
int colNum=1;
Sheet sheet = workbook.createSheet();
for (int i = 0; i < arr.length; i++) {
Row row = sheet.createRow(rowNum++);
Cell cell = row.createCell(colNum);
if (arr[i].contains("*")) {
//RED
cell.setCellStyle(headerCellStyleRed);
cell.setCellValue(arr[i].replace(".xml*", ""));
} else {
//GREEN
cell.setCellStyle(headerCellStyleGreen);
cell.setCellValue(arr[i].replace(".xml", ""));
}
row.setHeightInPoints(50);
}
FileOutputStream out = null;
if (workbook instanceof HSSFWorkbook) {
out = new FileOutputStream("CreateExcelCellStyleRedAndGreen.xls");
} else if (workbook instanceof XSSFWorkbook) {
out = new FileOutputStream("CreateExcelCellStyleRedAndGreen.xlsx");
}
workbook.write(out);
out.close();
workbook.close();
}
}

POI and setting cells to VerticalAlignment.MIDDLE

Hey all I am trying to get my cell to vertical line instead of just being aligned by the left side using POI.
This is my java code:
static CellStyle headerCellStyle = workbook.createCellStyle();
headerCellStyle = workbook.createCellStyle();
Row headerRow = null;
sheet = workbook.createSheet("String " + sheetname);
headerCellStyle.setWrapText(true);
headerCellStyle.setAlignment(HorizontalAlignment.LEFT);
headerCellStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);
headerCellStyle.setVerticalAlignment(VerticalAlignment.MIDDLE);
// Create a Row
headerRow = sheet.createRow(0);
However, the line headerCellStyle.setVerticalAlignment(VerticalAlignment.MIDDLE); has an error of:
The method setVerticalAlignment(org.apache.poi.ss.usermodel.VerticalAlignment) in the type CellStyle is not applicable for the arguments (org.apache.poi.sl.usermodel.VerticalAlignment)
How can i go about getting this to work if I have already defined it as an static CellStyle headerCellStyle = workbook.createCellStyle();?
Changing to SS does not seem to have the "middle" option?
This is the difference within excel for those 2 types:
The default way:
The Middle way (the way I am wanting):
The Center way:

Your second image (the way you want) shows CellStyle.setVerticalAlignment(VerticalAlignment.CENTER). Your third image shows CellStyle.setAlignment(HorizontalAlignment.CENTER).
There is a difference between setVerticalAlignment(VerticalAlignment.CENTER) and setAlignment(HorizontalAlignment.CENTER). The first sets vertical alignment to center (aka middle). The second sets horizontal alignment to center.
Complete Example:
import java.io.FileOutputStream;
import org.apache.poi.ss.usermodel.*;
import org.apache.poi.xssf.usermodel.XSSFWorkbook;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
class CreateExcelVerticalAlignment {
public static void main(String[] args) throws Exception {
// try (Workbook workbook = new XSSFWorkbook();
// FileOutputStream fileout = new FileOutputStream("Excel.xlsx") ) {
try (Workbook workbook = new HSSFWorkbook();
FileOutputStream fileout = new FileOutputStream("Excel.xls") ) {
CellStyle headerCellStyle = workbook.createCellStyle();
headerCellStyle = workbook.createCellStyle();
headerCellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
Sheet sheet = workbook.createSheet();
sheet.setColumnWidth(0, 20*256);
Row row = sheet.createRow(0);
row.setHeightInPoints(40);
Cell cell = row.createCell(0);
cell.setCellStyle(headerCellStyle);
cell.setCellValue("1082192560 1868");
workbook.write(fileout);
}
}
}
Result:

Exporting xlsx using apache poi 3.13 on weblogic : File format or extension not valid

Earlier I was using Apache POI 2.5.1 to export .xls file using HSSFWorkbook.
With updated Apache POI to 3.13 I am exporting .xlsx file using SXSSFWorkbook but its exporting corrupted file.
MS Excel failed to open file with File format or extension not valid error.
Note that this issue I am facing only on WebLogic server, it works fine with JBoss.
Anybody can help what I am doing wrong here ?
Code:
List<JRField> fields = ds.getFields();
SXSSFWorkbook wb = new SXSSFWorkbook();
SXSSFSheet sheet = wb.createSheet("Sheet1");
try {
CellStyle cellStyle = wb.createCellStyle();
CellStyle cellStyleColName = wb.createCellStyle();
CellStyle cellStyleTitle = wb.createCellStyle();
Font boldFont = wb.createFont();
boldFont.setFontHeightInPoints((short)16);
boldFont.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
// Cell Style for body
cellStyle.setDataFormat(HSSFDataFormat.getBuiltinFormat("($#,##0_);[Red]($#,##0)"));
cellStyle.setWrapText(true);
// Cell Style for Column Names
cellStyleColName.setDataFormat(HSSFDataFormat.getBuiltinFormat("($#,##0_);[Red]($#,##0)"));
cellStyleColName.setAlignment(HSSFCellStyle.ALIGN_CENTER);
cellStyleColName.setBorderTop(HSSFCellStyle.BORDER_MEDIUM); // single line border
cellStyleColName.setBorderBottom(HSSFCellStyle.BORDER_MEDIUM); // single line border
// Cell Style for Title
cellStyleTitle.setDataFormat(HSSFDataFormat.getBuiltinFormat("($#,##0_);[Red]($#,##0)"));
cellStyleTitle.setAlignment(HSSFCellStyle.ALIGN_CENTER);
cellStyleTitle.setFont(boldFont);
// Creating Title Row
Row row1 = sheet.createRow((short) 0);
// Creating the Title line
Cell cell1 = row1.createCell((short) 0);
cell1.setCellValue("Demo Title");
cell1.setCellStyle(cellStyleTitle);
// Title Region
CellRangeAddress regionTitle = new CellRangeAddress( (short) 0, // From Row
(short) 0, // From Col
(short) 0, // To Row
(short) (this.displayCols.size()-1) // To Col
);
sheet.addMergedRegion(regionTitle);
// Column Name Row
int j =0;
Row row2 = sheet.createRow((short) 1);
for (ReportColumn col : this.displayCols)
{
Cell cell2 = row2.createCell((short) j++);
cell2.setCellValue(col.getDisplayName());
cell2.setCellStyle(cellStyleColName);
}
int i =2;
while (ds.next()) {
Row rows = sheet.createRow((short) 0 + i);
int k = 0;
for (JRField field : fields) {
String fieldAsString = (ds.getFieldValue(field) != null ? ds.getFieldValue(field).toString():null);
Cell cell = rows.createCell((short) k++);
cell.setCellStyle(cellStyle);
cell.setCellValue(fieldAsString);
}
i++;
if (i > RECORD_LIMIT_FROM_POI){
log.info("Row limit from poi reached #1048576 and exported data is truncated.");
break;
}
}
wb.write(os);
}
catch (Exception e) {
log.error("error in createXlsFile method", e);
}
Failed attempts:
Updated mime type in response header from application/vnd.ms-excel
to vnd.openxmlformats-officedocument.spreadsheetml.sheet
Added xlsx=vnd.openxmlformats-officedocument.spreadsheetml.sheet in custom mime mapping file for WebLogic

This may be more resource heavy, but have you tried:
XSSFWorkbook wb = new SXSSFWorkbook();
XSSFSheet sheet = wb.createSheet("Sheet1");
instead of SXSSF.
There is some discussion between the various types here: HSSFWorkbook vs XSSFWorkbook and the advantages/disadvantages of XSSFWorkbook and SXSSFWorkbook?

Changing cell color using apache poi

I'm using Apache POI to read data in a spreadsheet of part numbers. I look up the part number in our database, if we have a CAD drawing of the part I color the part number cell green, if we don't I color it red. After the processing is done the spreadsheet is saved. The problem I'm having is that every cell in that column comes out green. I've stepped through the code, the logic to look up the part number is working fine and the logic to determine what color the cell should be and setting the color and fill appears to work as well. Any ideas what I'm doing wrong here?
Thanks.
//Check the parts
for(int r=1;r<sheet.getPhysicalNumberOfRows();r++) {
String partNumber = null;
switch(cell.getCellType()) {
case HSSFCell.CELL_TYPE_NUMERIC:
long pNum = (long) cell.getNumericCellValue();
partNumber = String.valueOf(pNum);
break;
case HSSFCell.CELL_TYPE_STRING:
partNumber = cell.getStringCellValue();
break;
default:
logger.info("Part Number at row " + r + " on sheet " + partList.getSheetName(s) + "is of an unsupported type");
}
try {
List<String> oldMaterialNumbers = getOldMaterialNumbers(partNumber);
boolean gotDrawing = checkPartNumber(oldMaterialNumbers, partNumber);
//If there's a drawing then color the row green, if not red.
short bgColorIndex = gotDrawing
?HSSFColor.LIGHT_GREEN.index //42
:HSSFColor.RED.index; //10
HSSFCell curCell = row.getCell(partNumberColumn);
HSSFCellStyle curStyle = curCell.getCellStyle();
curStyle.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
curStyle.setFillForegroundColor(bgColorIndex);
curCell.setCellStyle(curStyle);
}catch(Exception e) {
throw e;
}
}

Short version: Create styles only once, use them everywhere.
Long version: use a method to create the styles you need (beware of the limit on the amount of styles).
private static Map<String, CellStyle> styles;
private static Map<String, CellStyle> createStyles(Workbook wb){
Map<String, CellStyle> styles = new HashMap<String, CellStyle>();
DataFormat df = wb.createDataFormat();
CellStyle style;
Font headerFont = wb.createFont();
headerFont.setBoldweight(Font.BOLDWEIGHT_BOLD);
headerFont.setFontHeightInPoints((short) 12);
style = createBorderedStyle(wb);
style.setAlignment(CellStyle.ALIGN_CENTER);
style.setFont(headerFont);
styles.put("style1", style);
style = createBorderedStyle(wb);
style.setAlignment(CellStyle.ALIGN_CENTER);
style.setFillForegroundColor(IndexedColors.LIGHT_CORNFLOWER_BLUE.getIndex());
style.setFillPattern(CellStyle.SOLID_FOREGROUND);
style.setFont(headerFont);
style.setDataFormat(df.getFormat("d-mmm"));
styles.put("date_style", style);
...
return styles;
}
you can also use methods to do repetitive tasks while creating styles hashmap
private static CellStyle createBorderedStyle(Workbook wb) {
CellStyle style = wb.createCellStyle();
style.setBorderRight(CellStyle.BORDER_THIN);
style.setRightBorderColor(IndexedColors.BLACK.getIndex());
style.setBorderBottom(CellStyle.BORDER_THIN);
style.setBottomBorderColor(IndexedColors.BLACK.getIndex());
style.setBorderLeft(CellStyle.BORDER_THIN);
style.setLeftBorderColor(IndexedColors.BLACK.getIndex());
style.setBorderTop(CellStyle.BORDER_THIN);
style.setTopBorderColor(IndexedColors.BLACK.getIndex());
return style;
}
then, in your "main" code, set the style from the styles map you have.
Cell cell = xssfCurrentRow.createCell( intCellPosition );
cell.setCellValue( blah );
cell.setCellStyle( (CellStyle) styles.get("style1") );

To create your cell styles see: http://poi.apache.org/spreadsheet/quick-guide.html#CustomColors.
Custom colors
HSSF:
HSSFWorkbook wb = new HSSFWorkbook();
HSSFSheet sheet = wb.createSheet();
HSSFRow row = sheet.createRow((short) 0);
HSSFCell cell = row.createCell((short) 0);
cell.setCellValue("Default Palette");
//apply some colors from the standard palette,
// as in the previous examples.
//we'll use red text on a lime background
HSSFCellStyle style = wb.createCellStyle();
style.setFillForegroundColor(HSSFColor.LIME.index);
style.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);
HSSFFont font = wb.createFont();
font.setColor(HSSFColor.RED.index);
style.setFont(font);
cell.setCellStyle(style);
//save with the default palette
FileOutputStream out = new FileOutputStream("default_palette.xls");
wb.write(out);
out.close();
//now, let's replace RED and LIME in the palette
// with a more attractive combination
// (lovingly borrowed from freebsd.org)
cell.setCellValue("Modified Palette");
//creating a custom palette for the workbook
HSSFPalette palette = wb.getCustomPalette();
//replacing the standard red with freebsd.org red
palette.setColorAtIndex(HSSFColor.RED.index,
(byte) 153, //RGB red (0-255)
(byte) 0, //RGB green
(byte) 0 //RGB blue
);
//replacing lime with freebsd.org gold
palette.setColorAtIndex(HSSFColor.LIME.index, (byte) 255, (byte) 204, (byte) 102);
//save with the modified palette
// note that wherever we have previously used RED or LIME, the
// new colors magically appear
out = new FileOutputStream("modified_palette.xls");
wb.write(out);
out.close();
XSSF:
XSSFWorkbook wb = new XSSFWorkbook();
XSSFSheet sheet = wb.createSheet();
XSSFRow row = sheet.createRow(0);
XSSFCell cell = row.createCell( 0);
cell.setCellValue("custom XSSF colors");
XSSFCellStyle style1 = wb.createCellStyle();
style1.setFillForegroundColor(new XSSFColor(new java.awt.Color(128, 0, 128)));
style1.setFillPattern(CellStyle.SOLID_FOREGROUND);

I believe it is because cell.getCellStyle initially returns the default cell style which you then change.
Create styles like this and apply them to cells:
cellStyle = (XSSFCellStyle) cell.getSheet().getWorkbook().createCellStyle();
Although as the previous poster noted try and create styles and reuse them.
There is also some utility class in the XSSF library that will avoid the code I have provided and automatically try and reuse styles. Can't remember the class 0ff hand.

checkout the example here
http://svn.apache.org/repos/asf/poi/trunk/src/examples/src/org/apache/poi/ss/examples/BusinessPlan.java
style.setFillForegroundColor(IndexedColors.LIGHT_CORNFLOWER_BLUE.getIndex());

For apache POI 3.9 you can use the code bellow:
HSSFCellStyle style = workbook.createCellStyle()
style.setFillForegroundColor(HSSFColor.YELLOW.index)
style.setFillPattern((short) FillPatternType.SOLID_FOREGROUND.ordinal())
The methods for 3.9 version accept short and you should pay attention to the inputs.