使用Apache POI在Excel中开始新行的问题

Question

I'm using the apache poi package to create a spreadsheet of figures which represent features of a shape (area, perimeter, centroid). The problem is that i have a method: writeDatabase() which outputs the features of the shape as they are found, the output spreadsheet looks like this: http://s23.postimg.org/hqsfg76jv/Capture.png

All of these figures need to be in the same line, and then a new line needs to be taken for the next record. the writeDatabase method is shown below

public static void writeDatabase(int value, int cellNum){

    try {
        Cell cell1=null;
        FileInputStream file = new FileInputStream(new File("features.xls"));
        Workbook workbook = new HSSFWorkbook(file);
        Sheet sheet = workbook.getSheetAt(0);

        int lastRow = sheet.getPhysicalNumberOfRows();

        cell1 = sheet.createRow(lastRow).createCell(cellNum);
        cell1.setCellValue(value);

        FileOutputStream outFile =new FileOutputStream(new File("features.xls"));
        workbook.write(outFile);
        outFile.close();
    } catch (FileNotFoundException e) {
        e.printStackTrace();
    } catch (IOException e) {
        e.printStackTrace();
    }
}

I think the problem is with this line being called each time, but i cant think of an alternative: int lastRow = sheet.getPhysicalNumberOfRows();

Any ideas?

Answer 1

You need to provide some indication of whether a new line should be started or not (unless you can tell that a new line is starting simply because cellNum is 0?)

Then, you can either create a new row, or use the existing row:

    int lastRow = sheet.getPhysicalNumberOfRows();

    Row row;
    if (startNewRow) {
        row = sheet.createRow(lastRow);
    } else {
        row = sheet.getRow(lastRow - 1);
    }

    cell1 = row.createCell(cellNum);
    cell1.setCellValue(value);

Where startNewRow might be set based on cellNum , or might be an additional parameter that is passed into writeDatabase , whichever is appropriate.