How to add superscript text using Apache POI

You are thinking, RichTextString should be able to interpret HTML? It is not. It is only able to apply Font from startIndex to endIndex. And Font can be marked using TypeOffset SS_SUPER.

Example:

import org.apache.poi.xssf.usermodel.*;
import org.apache.poi.ss.usermodel.*;

import org.apache.poi.ss.util.*;

import java.io.FileOutputStream;

class RichTextSuperscript {

 public static void main(String[] args) {
  Workbook wb = new XSSFWorkbook();
  Sheet sheet = wb.createSheet("Sheet1");

  Font fontRed = wb.createFont();
  fontRed.setColor(Font.COLOR_RED);

  Font fontRedSuperscript = wb.createFont();
  fontRedSuperscript.setColor(Font.COLOR_RED);
  fontRedSuperscript.setTypeOffset(Font.SS_SUPER);

  String string = "Level 3";

  RichTextString richString = new XSSFRichTextString( "Level 13" );
                                                     //^0     ^7
  richString.applyFont(7, 8, fontRedSuperscript);

  for (int r = 0; r < 10; r++) {
   Row row = sheet.createRow(r);
   Cell cell = row.createCell(0);
   if ((r%2) == 0) {
    cell.setCellValue(string);
   } else {
    CellUtil.setFont(cell, fontRed);
    cell.setCellValue(richString);
   }
  }

  try {
   wb.write(new FileOutputStream("RichTextSuperscript.xlsx"));
   wb.close();
   } catch (Exception ex) {
   ex.printStackTrace();
  } 
 }
}