使用 Apache POI 编辑和现有 Excel 文件后，使用的公式会消失

Question

I am using Apache POI to edit an existing file. This file contains multiple formulas that use the numbers that will be inputted through Apache. And this is where I run into problems, when a number is inputted and that cell is being used in a formula, the file gets corrupted and the formula disappears. Here the formulas for the 0 are C7+D7, C8+D8, etc. Here the formulas for the 0 became normal 0, the formulas got lost.

Here is the code I used to write to the excel file:

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;

import org.apache.poi.EncryptedDocumentException;
import org.apache.poi.openxml4j.exceptions.InvalidFormatException;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.usermodel.WorkbookFactory;


public class write {
    public static void main(String[] args) {
        String excelFilePath = "C:\\Users\\jose_\\IdeaProjects\\writeExcel\\src\\JavaBooks.xlsx";

        try {
            FileInputStream inputStream = new FileInputStream(new File(excelFilePath));
            Workbook workbook = WorkbookFactory.create(inputStream);

            Sheet sheet = workbook.getSheetAt(0);
            /*Cell cell2Update = sheet.getRow(1).getCell(3); // This updates a specific cell: row 0 cell 3
            cell2Update.setCellValue(49);*/

            Object[][] bookData = {
                    {2, 17},
                    {3, 27},
                    {4, 33},
                    {5, 44},
            };

            // int rowCount = sheet.getLastRowNum(); // Gets the last entry
            int rowCount = 5;

            for (Object[] aBook : bookData) {
                Row row = sheet.createRow(++rowCount);

                int columnCount = 1;
                int lote = 1;

                Cell cell = row.createCell(columnCount);
                //cell.setCellValue(rowCount); // This sets the index for each entry
                cell.setCellValue(lote);

                for (Object field : aBook) {
                    cell = row.createCell(++columnCount);
                    if (field instanceof String) {
                        cell.setCellValue((String) field);
                    } else if (field instanceof Integer) {
                        cell.setCellValue((Integer) field);
                    }
                }

            }

            inputStream.close();

            FileOutputStream outputStream = new FileOutputStream("C:\\Users\\jose_\\IdeaProjects\\writeExcel\\src\\JavaBooks.xlsx");
            workbook.write(outputStream);
            workbook.close();
            outputStream.close();

        } catch (IOException | EncryptedDocumentException ex) {
            ex.printStackTrace();
        }

    }
}

Is there a way to work around this or do I need to set all the formulas again through Apache POI?

Answer 1

You get the error because using code line Row row = sheet.createRow(++rowCount); you always create new empty rows and so you remove all cells in those rows. So you are also removing the cells containing the formulas. Doing so you are damaging the calculation chain. That's what the Excel GUI tells you with the messages.

You should not do this. Instead you always should try to get the rows first using Sheet.getRow . Only if that returns null then you need to create the row.

...
//Row row = sheet.createRow(++rowCount);
Row row = sheet.getRow(rowCount); if (row == null) row = sheet.createRow(rowCount); rowCount++;
...

Additional please read Recalculation of Formulas . So after changing cells referenced in formulas, do always either workbook.getCreationHelper().createFormulaEvaluator().evaluateAll(); or delegate re-calculation to Excel using workbook.setForceFormulaRecalculation(true); .