使用Apache POI更新Excel文件

Question

我正在尝试使用Apache
POI更新现有的Excel文件。每次我运行代码时，都会收到如下所示的错误。我也试过FileInputStreamNewFile的东西。

Exception in thread "main" java.lang.NullPointerException
    at com.gma.test.WriteExcelTest.writeXLSXFile(WriteExcelTest.java:26)
    at com.gma.test.WriteExcelTest.main(WriteExcelTest.java:44)

请在下面找到代码。感谢你的帮助。

package com.gma.test;

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.XSSFCell;
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:\\Anuj\\Data\\Data.xlsx");

            XSSFWorkbook workbook = new XSSFWorkbook(file);
            XSSFSheet sheet = workbook.getSheetAt(0);
            Cell cell = null;

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

            file.close();

            FileOutputStream outFile =new FileOutputStream(new File("C:\\Anuj\\Data\\Data.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);
    }

}

Answer 1

如果您更换

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

用

//Retrieve the row and check for null
HSSFRow 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");

会工作的！