Setting foreground color for HSSFCellStyle is always coming out black

Question

I am using POI to create an Excel spreadsheet in Java. I have the following code used for creating a header row:

HSSFWorkbook wb = new HSSFWorkbook();
HSSFSheet sheet = wb.createSheet("Report");

// some more code

HSSFRow row = sheet.createRow(0);

HSSFCell cell = row.createCell(cellNumber);
HSSFCellStyle cellStyle = wb.createCellStyle();

cellStyle.setFillBackgroundColor(HSSFColor.GREY_25_PERCENT.index);
cellStyle.setFillPattern(HSSFCellStyle.SOLID_FOREGROUND);

HSSFFont font = wb.createFont();
font.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
font.setColor(HSSFColor.WHITE.index);

cellStyle.setFont(font);
cell.setCellStyle(cellStyle);

The issue I am having is that setting the fill background color on the cell always comes out black, no matter what color I pick. What am I doing wrong? If I don't use the "setFillPattern" line, no color shows up at all.

Answer 1

I got this to work. I had to set the foreground color to make the background color work (??).

So I changed:

cellStyle.setFillBackgroundColor(HSSFColor.GREY_25_PERCENT.index);

to:

cellStyle.setFillForegroundColor(HSSFColor.GREY_25_PERCENT.index);

and it worked!

Answer 2

If you are setting the foreground color, use

cellStyle.setFillPattern(FillPatternType.SOLID_FOREGROUND);

If you are setting the background color, use

style.setFillPattern(FillPatternType.THICK_BACKWARD_DIAG);

or

style.setFillPattern(FillPatternType.THIN_BACKWARD_DIAG);

The foreground and background colors seem to 'stack' (red + blue = purple) if you set the foreground fill pattern before the background fill pattern, but not the other way round. There are several other fill patterns you can choose from. Note that the color will not be applied if you do not change the default fill pattern.

CellStyle.SOLID_FOREGROUND is deprecated in version 3.15+. Use FillPatternType.SOLID_FOREGROUND instead.