Updating excel file using Apache POI

If you replace

//Update the value of cellcell = sheet.getRow(row).getCell(col);cell.setCellValue("Pass");

With

//Retrieve the row and check for nullHSSFRow sheetrow = sheet.getRow(row);if(sheetrow == null){    sheetrow = sheet.createRow(row);}//Update the value of cellcell = sheetrow.getCell(col);if(cell == null){    cell = sheetrow.createCell(col);}cell.setCellValue("Pass");

It will work!

Thanks Jelle Heuzel for getting a good example.
I just wanted to add the resulting working code so other can incorporate it in their code faster.

I also had to use XSSFRow instead of HSSFRow but other than that it works fine for me.

package stackoverflow.appachePOI;import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import org.apache.poi.ss.usermodel.Cell;import org.apache.poi.xssf.usermodel.XSSFRow;import org.apache.poi.xssf.usermodel.XSSFSheet;import org.apache.poi.xssf.usermodel.XSSFWorkbook;public class WriteExcelTest {    public static void writeXLSXFile(int row, int col) throws IOException {        try {            FileInputStream file = new FileInputStream("C:\\Users\\Sam\\files\\Masterproef lca\\lca-analysebeheer\\Test-Files\\exceltemplates\\template.xlsx");            XSSFWorkbook workbook = new XSSFWorkbook(file);            XSSFSheet sheet = workbook.getSheetAt(0);            Cell cell = null;            //Retrieve the row and check for null            XSSFRow sheetrow = sheet.getRow(row);            if(sheetrow == null){                sheetrow = sheet.createRow(row);            }            //Update the value of cell            cell = sheetrow.getCell(col);            if(cell == null){                cell = sheetrow.createCell(col);            }            cell.setCellValue("Pass");            file.close();            FileOutputStream outFile =new FileOutputStream(new File("C:\\Users\\Sam\\files\\Masterproef lca\\lca-analysebeheer\\Test-Files\\exceltemplates\\Output.xlsx"));            workbook.write(outFile);            outFile.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }    public static void main(String[] args) throws IOException {        // TODO Auto-generated method stub        writeXLSXFile(3, 3);    }}

i tried with this and work for XLSX and XSSF

import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import org.apache.poi.ss.usermodel.Cell;import org.apache.poi.xssf.usermodel.XSSFRow;import org.apache.poi.xssf.usermodel.XSSFSheet;import org.apache.poi.xssf.usermodel.XSSFWorkbook;public class TestStackOver {    public static void writeXLSXFile(int row, int col) throws IOException {        try {            FileInputStream file = new FileInputStream(Constante.ruta);            XSSFWorkbook workbook = new XSSFWorkbook(file);            XSSFSheet sheet = workbook.getSheetAt(0);            Cell cell = null;          //Retrieve the row and check for null            XSSFRow sheetrow = sheet.getRow(row);            if(sheetrow == null){                sheetrow = sheet.createRow(row);            }            //Update the value of cell            cell = sheetrow.getCell(col);            if(cell == null){                cell = sheetrow.createCell(col);            }            cell.setCellValue("Pass");            file.close();            FileOutputStream outFile =new FileOutputStream(new File(Constante.ruta_salida));            workbook.write(outFile);            outFile.close();        } catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }    }    public static void main(String[] args) throws IOException {        // TODO Auto-generated method stub        System.out.println("inicio");        writeXLSXFile(1, 14);        System.out.println("terminado");    }}