c# – List Box Selected.value抛出null异常

发布时间：2020-12-16 01:53:48 所属栏目：百科来源：网络整理

导读：填充列表框如下： if (ds != null){ ListPreviousRecords.Items.Clear(); ListPreviousRecords.DataSource = ds; ListPreviousRecords.DataTextField = "Date"; ListPreviousRecords.DataValueField = "ID"; ListPreviousRecords.DataBind();} 获取选定值：

填充列表框如下：

if (ds != null)
{
    ListPreviousRecords.Items.Clear();

    ListPreviousRecords.DataSource = ds;
    ListPreviousRecords.DataTextField = "Date";
    ListPreviousRecords.DataValueField = "ID";
    ListPreviousRecords.DataBind();
}

获取选定值：

protected void ListPreviousRecords_OnSelectedIndexChanged(object sender,EventArgs e)
{
    if(ListPreviousRecords.SelectedItem.Value != "")
    {
        int mySelectedValue = int.Parse(ListPreviousRecords.SelectedItem.Value);// throwing null exception
        loadPreviousDetails(mySelectedValue);
    }
}

解决方法

您可以添加此代码以确保输入非空值

if(!string.IsNullOrEmpty(ListPreviousRecords.SelectedItem.Value ))
{
...
}

并确保在您的控件上设置了AutoPostBack =“true”

链接：http://msdn.microsoft.com/fr-fr/library/system.string.isnullorempty.aspx

（编辑：李大同）

【声明】本站内容均来自网络，其相关言论仅代表作者个人观点，不代表本站立场。若无意侵犯到您的权利，请及时与联系站长删除相关内容!