Question

I’m writing an application which reads data from a Microsoft Access database and writes this data into an Excel Sheet. Everything works fine but not the writing of the new data to the file. Here is the code:

private static XSSFWorkbook readFile(String filename) throws IOException {
    // return new XSSFWorkbook(new FileInputStream(filename));
    InputStream inp = new FileInputStream(filename);
    XSSFWorkbook wb = null;
    try {
        wb = (XSSFWorkbook) WorkbookFactory.create(inp);
    } catch (InvalidFormatException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }
    return wb;
}

public void writeToFile(LinkedList<TimeRowWrapper> list) {

    try {
        // read file
        XSSFWorkbook workbook = readFile(fileName);

        // choose table from index
        XSSFSheet sheet = workbook.getSheetAt(kapaSheetIndex);

        for (Row row : sheet) {
            int rowNum = row.getRowNum();

            // iterate over list for row id
            for (TimeRowWrapper trw : list) {
                if (rowNum == trw.getRowNumber()) {

                    double hour = Math
                            .round(trw.getTotalTime() / 60.0 * 100.) / 100.;
                    Cell cell = row.getCell(timeCol);
                    cell.setCellValue(hour);
                }
            }
        }

        XSSFFormulaEvaluator.evaluateAllFormulaCells(workbook);

        FileOutputStream out = new FileOutputStream(fileName);
        workbook.write(out);
        out.close();

    } catch (IOException e) {
        e.printStackTrace();
    } catch (NullPointerException e) {
        e.printStackTrace();
    } catch (NumberFormatException e) {
        e.printStackTrace();
    }
}

Answer 1

The sourcecode I posted was correct. In the Excelfile were some Colums with the withe of 0 – so I tryed to write in a column which was not shown.