DropDownList控件

1、DropDownList控件

<asp:DropDownList runat="server" ID="DropDownList1" AutoPostBack="true" OnSelectedIndexChanged="DropDownList_SelectedIndexChanged"></asp:DropDownList>

  public partial class _Default : System.Web.UI.Page

  {

  protected void Page_Load(object sender, EventArgs e)

  {

  if (!IsPostBack)

  {

  ArrayList color = new ArrayList();

  color.Add("Red");

  color.Add("Green");

  color.Add("Blue");

  color.Add("LightGray");

  DropDownList1.DataSource = color;

  DropDownList1.DataBind();

  }

  }

  protected void DropDownList_SelectedIndexChanged(object sender, EventArgs e)

  {

  string color = this.DropDownList1.SelectedItem.Value;

  switch (color)

  {

  case "Red":

  this.DropDownList1.BackColor = System.Drawing.Color.Red;

  break;

  case "Green":

  this.DropDownList1.BackColor = System.Drawing.Color.Green;

  break;

  case "Blue":

  this.DropDownList1.BackColor = System.Drawing.Color.Blue;

  break;

  case "LightGray":

  this.DropDownList1.BackColor = System.Drawing.Color.LightGray;

  break;

  default:

  this.DropDownList1.BackColor = System.Drawing.Color.White;

  break;

  }

  }

  }

(1)获取DropDownList控件选项的索引号和标题

int Index = DropDownList1.SelectedIndex;//获取选项的索引号

int Index = DropDownList1.SelectedItem;//获取选项的标题

(2)向 DropDownList控件的下拉列表框中添加列表项

DropDownList1.Items.Add(new ListItem(“ASP.NET”,”0″));

DropDownList1.Items.Add(new ListItem(“VB.NET”,”1″));

DropDownList1.Items.Add(new ListItem(“C#.NET”,”2″));

DropDownList1.Items.Add(new ListItem(“VB”,”3″));

(3)删除选项的DropDownList控件的列表项

ListItem Item = DropDownList1.SelectedItem;

DropDownList1.Items.Remove(Item);

(4)清除所有DropDownList控件的列表项

DropDownList1.Items.Clear();

(5)获取DropDownList控件包含的列表项数

int count = DropDownList1.Items.Count;

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