DropDownList.SelectedIndex 属性

定义

获取或设置 DropDownList 控件中的选定项的索引。Gets or sets the index of the selected item in the DropDownList control.

public:
 virtual property int SelectedIndex { int get(); void set(int value); };
public override int SelectedIndex { get; set; }
member this.SelectedIndex : int with get, set
Public Overrides Property SelectedIndex As Integer

属性值

DropDownList 控件中的选定项的索引。The index of the selected item in the DropDownList control. 默认值为 0,该值选择列表中的第一项。The default value is 0, which selects the first item in the list.

示例

下面的代码示例演示如何使用SelectedIndex属性来确定DropDownList控件中的选定项。The following code example demonstrates how to use the SelectedIndex property to determine the selected item in the DropDownList control.

<%@ Page Language="C#" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
   <script runat="server" >
  
      void Selection_Change(Object sender, EventArgs e)
      {

         // Set the title format based on the value selected from the
         // DropDownList control. The SelectedIndex property can be used
         // to determine an enumeration value. Simply cast the value to 
         // the appropriate enumeration type. Note that the value might
         // need to be adjusted if the enumeration type is not zero-based. 
         Calendar1.TitleFormat = (TitleFormat)ModeList.SelectedIndex;

      }
  
   </script>
  
<head runat="server">
    <title> DropDownList SelectedIndex Example </title>
</head>
<body>

   <form id="form1" runat="server">
  
      <h3> DropDownList SelectedIndex Example </h3>

      Choose the title format.

      <br /><br /> 
  
      <asp:Calendar id="Calendar1"
           ShowGridLines="True" 
           ShowTitle="True"
           runat="server"/>

      <br /><br />

      <table cellpadding="5">

         <tr>

            <td>

               Format:

            </td>

         </tr>

         <tr>

            <td>

               <asp:DropDownList id="ModeList"
                    AutoPostBack="True"
                    OnSelectedIndexChanged="Selection_Change"
                    runat="server">

                  <asp:ListItem> Month </asp:ListItem>
                  <asp:ListItem Selected="True"> MonthYear </asp:ListItem>

               </asp:DropDownList>

            </td>

         </tr>
         
      </table>   
  
   </form>

</body>
</html>
 
<%@ Page Language="VB" AutoEventWireup="True" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" >
   <script runat="server" >
  
      Sub Selection_Change(sender As Object, e As EventArgs)
      
         ' Set the title format based on the value selected from the
         ' DropDownList control. The SelectedIndex property can be used
         ' to determine an enumeration value. Simply cast the value to 
         ' the appropriate enumeration type. Note that the value might
         ' need to be adjusted if the enumeration type is not zero-based.
         Calendar1.TitleFormat = CType(ModeList.SelectedIndex, TitleFormat)

      End Sub
  
   </script>
  
<head runat="server">
    <title> DropDownList SelectedIndex Example </title>
</head>
<body>

   <form id="form1" runat="server">
  
      <h3> DropDownList SelectedIndex Example </h3>

      Choose the title format.

      <br /><br /> 
  
      <asp:Calendar id="Calendar1"
           ShowGridLines="True" 
           ShowTitle="True"
           runat="server"/>

      <br /><br />

      <table cellpadding="5">

         <tr>

            <td>

               Format:

            </td>

         </tr>

         <tr>

            <td>

               <asp:DropDownList id="ModeList"
                    AutoPostBack="True"
                    OnSelectedIndexChanged="Selection_Change"
                    runat="server">

                  <asp:ListItem> Month </asp:ListItem>
                  <asp:ListItem Selected="True"> MonthYear </asp:ListItem>

               </asp:DropDownList>

            </td>

         </tr>
         
      </table>   
  
   </form>

</body>
</html>
 

注解

使用属性以编程方式指定或确定DropDownList控件中选定项的索引。 SelectedIndexUse the SelectedIndex property to programmatically specify or determine the index of the selected item from the DropDownList control. 始终在DropDownList控件中选择项。An item is always selected in the DropDownList control. 不能同时清除列表中的每个项的选择。You cannot clear the selection from every item in the list at the same time.

备注

DropDownList控件中项的索引从零开始。The indexes for the items in the DropDownList control are zero-based.

适用于

另请参阅