c# winforms VS2017 链接 excel : error when closing form

Question

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这被认为是重复的帖子，因为确切的代码用于另一个问题(大约 5 年前)。基本上，我收到错误 System.NullreferenceException: 'Object reference not set to an instance on an object '. 行 xlWorkBook.Close(true, misValue, misValue); 每次我关闭表单时(见图)。基于原始问题:Inserting multiple textbox data into an Excel file ，我找不到其他人和我有同样的问题。我使用的代码与链接相同:

`using System;
 using System.Collections.Generic;
 using System.ComponentModel;
 using System.Data;
 using System.Drawing;
 using System.Linq;
 using System.Text;
 using Excel = Microsoft.Office.Interop.Excel;
 using System.Windows.Forms;

 namespace Vehicledettry
   {
     public partial class Form1 : Form
      {
    Microsoft.Office.Interop.Excel.Application xlexcel;
    Microsoft.Office.Interop.Excel.Workbook xlWorkBook;
    Microsoft.Office.Interop.Excel.Worksheet xlWorkSheet;
    object misValue = System.Reflection.Missing.Value;

    public Form1()
    {
        InitializeComponent();
    }

    private void button1_Click(object sender, EventArgs e)
    {
        xlexcel = new Excel.Application();

        xlexcel.Visible = true;

        // Open a File
        xlWorkBook = xlexcel.Workbooks.Open(" C:\\vehicledet.xlsx", 0, true, 5, "", "", true,
        Microsoft.Office.Interop.Excel.XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0);

        xlWorkSheet = (Excel.Worksheet)xlWorkBook.Worksheets.get_Item(1);

        xlWorkSheet.Cells[1, 1] = "Plate Number";
        xlWorkSheet.Cells[1, 2] = "Car Model";
        xlWorkSheet.Cells[1, 3] = "Car Brand";
        xlWorkSheet.Cells[1, 4] = "Mileage";
    }

    private void button2_Click(object sender, EventArgs e)
    {
        int _lastRow = xlWorkSheet.Cells[xlWorkSheet.Rows.Count, 1].End[Excel.XlDirection.xlUp].Row + 1;

        xlWorkSheet.Cells[_lastRow, 1] = Plate Number.Text;
        xlWorkSheet.Cells[_lastRow, 2] = Car Model.Text;
        xlWorkSheet.Cells[_lastRow, 3] = Car Brand.Text;
        xlWorkSheet.Cells[_lastRow, 4] = Mileage.Text;

    }

    private void button3_Click(object sender, EventArgs e)
    {
        xlWorkBook.Close(true, misValue, misValue);
        xlexcel.Quit();

        releaseObject(xlWorkSheet);
        releaseObject(xlWorkBook);
        releaseObject(xlexcel);

    }

    private void releaseObject(object obj)
    {
        try
        {
            System.Runtime.InteropServices.Marshal.ReleaseComObject(obj);
            obj = null;
        }
        catch (Exception ex)
        {
            obj = null;
            MessageBox.Show("Unable to release the Object " + ex.ToString());
        }
        finally
        {
            GC.Collect();
        }
    }

}

我试过复制 xlWorkBook = xlexcel.Workbooks.Open("C:\\vehicledet.xlsx", 0, true, 5, "", "", true, Microsoft.Office.Interop.Excel .XlPlatform.xlWindows, "\t", false, false, 0, true, 1, 0); 在每个按钮事件点击后，但同样的错误不断发生。希望我能得到一些帮助。谢谢。

Answer 1

最近，我还有一个项目会将数据发送到 excel 文件中，但与您的不同，我的数据来自文本文件，此站点上的某人帮助我弄清楚如何导出数组的值在 Excel 文件中。在您的情况下，这段代码可能会有所帮助。

using Excel = Microsoft.Office.Interop.Excel;
Excel.Application exc = new Excel.Application();
exc.Interactive = true;
var excelTemplate = "CompareResult.xlsx"; //Change it with your filename
string FromPath = Path.GetFullPath(excelTemplate); //Get the full path of your excel 
//file.
Excel.Workbook wb = exc.Workbooks.Open(FromPath);
Excel.Worksheet sh = wb.Sheets[1];
int _lastRow = xlWorkSheet.Cells[xlWorkSheet.Rows.Count, 1].End[Excel.XlDirection.xlUp].Row + 1;
sh.Cells[row, 1].Value2 = textBox1.Text;
sh.Cells[row, 2].Value2 = textBox1.Text;
sh.Cells[row, 3].Value2 = textBox1.Text;
sh.Cells[row, 4].Value2 = textBox1.Text;
wb.Save(); \\Saving the file when changing
wb.Close(); 
exc.Quit();