通过datagridview搜索无法正常工作 - System.NullReferenceException错误

Question

我正在尝试通过我的datagridview上的第2列（数据类型：数字）运行搜索，但不断收到以下错误消息：

An unhandled exception of type 'System.NullReferenceException' occurred in SpeedyRent.exe
Additional information: Object reference not set to an instance of an object.

错误发生在if (!string.Equals(row.Cells[1].Value.ToString(), driverNo.Text, StringComparison.OrdinalIgnoreCase))

我做错了什么？我在下面提供了我的代码：

    void driverSearch()
    {
        CurrencyManager manager = (CurrencyManager)BindingContext[dataGridView1.DataSource];
        manager.SuspendBinding();
        bool shouldNotFilter = string.IsNullOrEmpty(driverNo.Text);
        foreach (DataGridViewRow row in dataGridView1.Rows)
        {
            if (shouldNotFilter)
            {
                row.Visible = true;
            }
            else
            {
                if (!string.Equals(row.Cells[1].Value.ToString(), driverNo.Text, StringComparison.OrdinalIgnoreCase))
                {
                    row.Visible = false;
                }
                else
                {
                    row.Visible = true;
                }
            }
        }
        manager.ResumeBinding();
    }

    private void driverNo_KeyUp(object sender, KeyEventArgs e)
    {
        driverSearch();
    }

    private void driverNo_TextChanged(object sender, EventArgs e)
    {
        driverSearch();
    }

    private void driverNo_KeyPress(object sender, KeyPressEventArgs e)
    {
        if (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar))
        {
            e.Handled = true;
        }

        driverSearch();
    }

Answer 1

在foreach循环中尝试此块：

if (shouldNotFilter)
{
     row.Visible = true;
}
else
{
    if(row.Cells[1].Value == null)
    {
       row.Visible = false;
    }
    else
    {
         if (!string.Equals(row.Cells[1].Value.ToString(), driverNo.Text, StringComparison.OrdinalIgnoreCase))
         {
              row.Visible = false;
         }
         else
         {
              row.Visible = true;
         }
    }
}