Java Spring apache POI, store long number in excel without exponents

I would never storing numeric values as text. The requirement having numeric cell content with as much decimal places as needed and not switching to exponential would be fulfilled using the number format 0.0##############. Each # means: use this digit if needed. Digits before the decimal point are always showed if needed. So there only one 0 is necessary. The format means in whole: at least one digit before the decimal point and at least one decimal place but 15 further decimal places maximal if needed. Excel always stores floating point values only with up to 15 significant digits precision. Thats why more than 15 decimal places are not useful.

But if the requirement really is, storing numeric values as text, then this also is possible using the number format @. This is the "Text" number format. To avoiding "number stored as text" warning, the usage of XSSFSheet.addIgnoredErrors is possible if the Excel is of type XSSF.

Example:

import java.io.FileOutputStream;

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

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

public class ExcelStoreBigNumbers {

 public static void main(String[] args) throws Exception {
  String valueInput = "123456789012.12345";

  Workbook workbook = new XSSFWorkbook();
  Sheet sheet = workbook.createSheet();

  CellStyle style;
  DataFormat format = workbook.createDataFormat();
  Row row;
  Cell cell;

  //numeric cell value formatted having as much decimal places as needed
  style = workbook.createCellStyle();
  style.setDataFormat(format.getFormat("0.0##############"));
  row = sheet.createRow(0);
  cell = row.createCell(0);
  cell.setCellStyle(style);
  cell.setCellValue(Double.parseDouble(valueInput)); //precision only up to 15 significant digits

  //string cell value formatted as text
  style = workbook.createCellStyle();
  style.setDataFormat(format.getFormat("@"));
  row = sheet.createRow(1);
  cell = row.createCell(0);
  cell.setCellStyle(style);
  cell.setCellValue(valueInput);

  //avoiding "number stored as text" warning
  if (sheet instanceof XSSFSheet) {
   ((XSSFSheet)sheet).addIgnoredErrors(new CellReference(cell), IgnoredErrorType.NUMBER_STORED_AS_TEXT);
  }

  sheet.autoSizeColumn(0);

  workbook.write(new FileOutputStream("ExcelStoreBigNumbers.xlsx"));
  workbook.close(); 
 }

}