c# - "Cannot perform runtime binding on a null reference"读取/显示Excel

Question

我准备了一个简单的代码，用于将 excel 文件读取为 c# Wpf 格式。

但是我得到了错误:

{"Cannot perform runtime binding on a null reference"}.

下面是代码....

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;
using Excel = Microsoft.Office.Interop.Excel;
namespace WindowsFormsApplication9
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            Excel.Application xlApp = new Excel.Application();
            Excel.Workbook xlWorkbook = xlApp.Workbooks.Open("Book1.xlsx");
            Excel._Worksheet xlWorksheet = xlWorkbook.Sheets[1];
            Excel.Range xlRange = xlWorksheet.UsedRange;

            int rowCount = xlRange.Rows.Count;
            int colCount = xlRange.Columns.Count;

            for (int i = 1; i <= rowCount; i++)
            {
                for (int j = 1; j<= colCount; j++)
                {
                    MessageBox.Show(xlRange.Cells[i, j].Value2.ToString());
                }
            }
        }
    }
}

Answer 1

不要使用 .ToString() 方法。当值为null时会引发空引用异常。

使用可以使用Convert.ToString()