NullPointerException raised eventhough it is not NULL

Question

NullPointerException raise while trying update a excel cell using Apache POI. Particular cell that I want to update has some value but I can't update due to exception.

String excelFileName = "D:\\TempLocation\\Marks.xlsx";//name of excel file
String sheetName = "Sheet1";//name of sheet
XSSFWorkbook wb = new XSSFWorkbook();
XSSFSheet sheet = wb.getSheet(sheetName) ;
System.out.println(regNo+ " " + cellNo);
Cell cellToUpdate = sheet.getRow(0).getCell(0);
cellToUpdate.setCellValue(mark);
FileOutputStream fileOut = new FileOutputStream(excelFileName);
//write this workbook to an Outputstream.
wb.write(fileOut);
fileOut.flush();
fileOut.close();

this is my code. Exception raised at this line:

Cell cellToUpdate = sheet.getRow(0).getCell(0);

They are 3 possible reasons. I recommend you to go step by step. First, `sheet` might be null, Secod, maybe sheet doesnt have row `0`, Third, maybe there is no cell `0` — Luis felipe De jesus Munoz, May 07 '18 at 12:59
Can you print `sheet.getRow(0)` and after that `sheet.getRow(0).getCell(0)` later? — Harshit, May 07 '18 at 12:59
`sheet` is `null` because you have not create one ! use `wb.createSheet()` before `wb.getSheet(sheetName)` or pass your file in constructor of `wb` — Dams, May 07 '18 at 13:13
Did you try stepping through the code with a debugger to see what the values were? — EJoshuaS - Stand with Ukraine, May 07 '18 at 13:16
@dams You are right. Sheet is null as I didn't pass any parameter to wb.getSheet(); Now it gets working after passing. — Udhaya, May 07 '18 at 13:26

score 0 · Accepted Answer · answered May 07 '18 at 13:29

0

Inclusion of this line

FileInputStream  fis = new FileInputStream(new File(excelFileName));

And changes in this line

XSSFWorkbook wb = new XSSFWorkbook(fis);

Makes it to work.

answered May 07 '18 at 13:29

Udhaya

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NullPointerException raised eventhough it is not NULL

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