ASP.NET DropDownList FindByValue 未将对象引用设置到对象的实例 解决方法

3、数据源中确实没有找到该值。那就该加非Null判断了，代码如下：

<span style="color: #008080;"> 1</span>  BLL.Student bllStu = <span style="color: #0000ff;">new</span><span style="color: #000000;"> BLL.Student();
</span><span style="color: #008080;"> 2</span>  <span style="color: #008000;">//</span><span style="color: #008000;">设置数据源</span>
<span style="color: #008080;"> 3</span>  StuDDL.DataSource =<span style="color: #000000;"> bllStu.GetStudentList();
</span><span style="color: #008080;"> 4</span>  <span style="color: #008000;">//</span><span style="color: #008000;">设置显示数据字段名称</span>
<span style="color: #008080;"> 5</span>  StuDDL.DataTextField = <span style="color: #800000;">"</span><span style="color: #800000;">StuName</span><span style="color: #800000;">"</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 6</span>  <span style="color: #008000;">//</span><span style="color: #008000;">设置Value值字段名称</span>
<span style="color: #008080;"> 7</span>  StuDDL.DataValueField = <span style="color: #800000;">"</span><span style="color: #800000;">StuId</span><span style="color: #800000;">"</span><span style="color: #000000;">;
</span><span style="color: #008080;"> 8</span>  <span style="color: #008000;">//</span><span style="color: #008000;">绑定</span>
<span style="color: #008080;"> 9</span> <span style="color: #000000;"> StuDDL.DataBind();
</span><span style="color: #008080;">10</span>  <span style="color: #008000;">//获取</span><span style="color: #008000;">选中值</span>
<span style="color: #008080;">11</span>  <span style="color: #0000ff;">object</span> findValue=<span style="color: #000000;">StuDDL.Items.FindByValue(stuId);
</span><span style="color: #008080;">12</span>  <span style="color: #0000ff;">if</span>(findValue!=<span style="color: #0000ff;">null</span><span style="color: #000000;">)
</span><span style="color: #008080;">13</span> <span style="color: #000000;"> {
</span><span style="color: #008080;">14</span>  　　findValue.Selected = <span style="color: #0000ff;">true</span><span style="color: #000000;">;
</span><span style="color: #008080;">15</span> <span style="color: #000000;"> }</span>

ASP.NET DropDownList FindByValue 未将对象引用设置到对象的实例 解决方法

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