Use setFillBackGroundColor() and setFillForeGroundColor() together

I'm using Apache POI 5.2.3 and want to create a cell with green background and white foreground (text).

I created a document that had a cell with green background and black text:

var workbook = new XSSFWorkbook();
var style = workbook.createCellStyle();
style.setFillBackgroundColor(IndexedColors.BRIGHT_GREEN.getIndex());
style.setFillPattern(FillPatternType.BIG_SPOTS);
cell.setCellValue("test");
cell.setStyle(style);

Then I tried to change the text color, but it didn't change:

var style = workbook.createCellStyle();
style.setFillBackgroundColor(IndexedColors.BRIGHT_GREEN.getIndex());
style.setForeBackgroundColor(IndexedColors.WHITE.getIndex());
style.setFillPattern(FillPatternType.BIG_SPOTS);
cell.setCellValue("test");
cell.setStyle(style);

After the following change the whole cell became black:

var style = workbook.createCellStyle();
style.setFillBackgroundColor(IndexedColors.BRIGHT_GREEN.getIndex());
style.setForeBackgroundColor(IndexedColors.WHITE.getIndex());
style.setFillPattern(FillPatternType.BIG_SPOTS);
style.setFillPattern(FillPatternType.SOLID_FOREGROUND);
cell.setCellValue("test");
cell.setStyle(style);

I'm out of ideas how to accomplish this task

In Excel cell interiors have pattern fills. There the fill foreground color is the color of the pattern while fill background color is the color behind the pattern. Neither fill foreground color nor fill background color is the color of the text. The color of the text is the font color.

So using FillPatternType.SOLID_FOREGROUND the pattern is solid and only the solid pattern is viewable in fill foreground color. Using other pattern types the pattern are in fill foreground color while the background behind the pattern is in fill background color.

The following code shows all this. Your requirement "to create a cell with green background and white foreground (text)" needs a solid pattern fill having fill foreground color green and text using a font having white color.

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 UnderstandExcelCellInteriors {
public static void main(String[] args) throws Exception {
Workbook workbook = new XSSFWorkbook(); FileOutputStream out = new FileOutputStream("UnderstandExcelCellInteriors.xlsx");
CellStyle cellStyle = workbook.createCellStyle();
cellStyle.setAlignment(HorizontalAlignment.CENTER);
cellStyle.setVerticalAlignment(VerticalAlignment.CENTER);
Font whiteFont = workbook.createFont();
whiteFont.setColor(IndexedColors.WHITE.getIndex());
CellStyle cellStyle1 = workbook.createCellStyle();
cellStyle1.cloneStyleFrom(cellStyle);
cellStyle1.setFillForegroundColor(IndexedColors.BRIGHT_GREEN.getIndex()); //FillForegroundColor is the color of the pattern
cellStyle1.setFillPattern(FillPatternType.SOLID_FOREGROUND); //solid pattern means cell fill is FillForegroundColor only
CellStyle cellStyle2 = workbook.createCellStyle();
cellStyle2.cloneStyleFrom(cellStyle);
cellStyle2.setFillBackgroundColor(IndexedColors.YELLOW.getIndex()); //FillBackgroundColor is the color behind the pattern
cellStyle2.setFillForegroundColor(IndexedColors.BLUE.getIndex()); //FillForegroundColor is the color of the pattern
cellStyle2.setFillPattern(FillPatternType.BIG_SPOTS); //big spots pattern in blue in front of yellow background
CellStyle cellStyle3 = workbook.createCellStyle();
cellStyle3.cloneStyleFrom(cellStyle);
cellStyle3.setFillForegroundColor(IndexedColors.GREEN.getIndex()); //FillForegroundColor is the color of the pattern
cellStyle3.setFillPattern(FillPatternType.SOLID_FOREGROUND); //solid pattern means cell fill is FillForegroundColor only
cellStyle3.setFont(whiteFont); //white text color via font
Sheet sheet = workbook.createSheet();
Row row = sheet.createRow(0);
Cell cell = row.createCell(0);
cell.setCellValue("cell value");
cell.setCellStyle(cellStyle1);
cell = row.createCell(1);
cell.setCellValue("cell value");
cell.setCellStyle(cellStyle2);
cell = row.createCell(2);
cell.setCellValue("cell value");
cell.setCellStyle(cellStyle3);
row.setHeightInPoints(50);
sheet.setColumnWidth(0, 50 * 256);
sheet.setColumnWidth(1, 50 * 256);
sheet.setColumnWidth(2, 50 * 256);
workbook.write(out);
out.close();
workbook.close();
}
}