.NET Framework Class Library
ListItemCollection Class

A collection of ListItem objects in a list control. This class cannot be inherited.

Inheritance Hierarchy
SystemObject
  System.Web.UI.WebControlsListItemCollection

Namespace:   System.Web.UI.WebControls
Assembly:  System.Web (in System.Web.dll)
Syntax
Public NotInheritable Class ListItemCollection _
	Implements [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_0_0_0%], [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_0_0_1%], [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_0_0_2%], [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_0_0_3%]
public sealed class ListItemCollection : [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_1_0_0%], 
	[%$TOPIC/ez4tsddk_en-us_VS_110_3_0_1_0_1%], [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_1_0_2%], [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_1_0_3%]
public ref class ListItemCollection sealed : [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_2_0_0%], 
	[%$TOPIC/ez4tsddk_en-us_VS_110_3_0_2_0_1%], [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_2_0_2%], [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_2_0_3%]
[<[%$TOPIC/ez4tsddk_en-us_VS_110_3_0_3_0_0%]>]
type ListItemCollection =  
    class 
        interface [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_3_0_1%] 
        interface [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_3_0_2%] 
        interface [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_3_0_3%] 
        interface [%$TOPIC/ez4tsddk_en-us_VS_110_3_0_3_0_4%] 
    end

The ListItemCollection type exposes the following members.

Constructors
  NameDescription
Public method ListItemCollectionInitializes a new instance of the ListItemCollection class.
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Properties
  NameDescription
Public property CapacityGets or sets the maximum number of items that the ListItemCollection can store.
Public property CountGets the number of ListItem objects in the collection.
Public property IsReadOnlyGets a value indicating whether the ListItemCollection is read-only.
Public property IsSynchronizedGets a value indicating whether access to the ListItemCollection is synchronized (thread-safe).
Public property ItemGets a ListItem at the specified index in the collection.
Public property SyncRootGets the object that can be used to synchronize access to the ListItemCollection.
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Methods
  NameDescription
Public method Add(ListItem)Appends the specified ListItem to the end of the collection.
Public method Add(String)Appends a ListItem to the end of the collection that represents the specified string.
Public method AddRangeAdds the items in an array of ListItem objects to the collection.
Public method ClearRemoves all ListItem objects from the collection.
Public method ContainsDetermines whether the collection contains the specified item.
Public method CopyToCopies the items from the ListItemCollection to the specified SystemArray, starting with the specified index.
Public method Equals(Object)Determines whether the specified object is equal to the current object. (Inherited from Object.)
Public method FindByTextSearches the collection for a ListItem with a Text property that equals the specified text.
Public method FindByValueSearches the collection for a ListItem with a Value property that contains the specified value.
Public method GetEnumeratorReturns a System.CollectionsIEnumerator implemented object that contains all ListItem objects in the ListItemCollection.
Public method GetHashCodeServes as the default hash function. (Inherited from Object.)
Public method GetTypeGets the Type of the current instance. (Inherited from Object.)
Public method IndexOfDetermines the index value that represents the position of the specified ListItem in the collection.
Public method Insert(Int32, String)Inserts a ListItem which represents the specified string in the collection at the specified index location.
Public method Insert(Int32, ListItem)Inserts the specified ListItem in the collection at the specified index location.
Public method Remove(ListItem)Removes the specified ListItem from the collection.
Public method Remove(String)Removes a ListItem from the collection that represents the specified string.
Public method RemoveAtRemoves the ListItem at the specified index from the collection.
Public method ToStringReturns a string that represents the current object. (Inherited from Object.)
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Extension Methods
  NameDescription
Public Extension Method AsParallelEnables parallelization of a query. (Defined by ParallelEnumerable.)
Public Extension Method AsQueryableConverts an IEnumerable to an IQueryable. (Defined by Queryable.)
Public Extension Method CastTResultCasts the elements of an IEnumerable to the specified type. (Defined by Enumerable.)
Public Extension Method OfTypeTResultFilters the elements of an IEnumerable based on a specified type. (Defined by Enumerable.)
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Explicit Interface Implementations
  NameDescription
Explicit interface implemetation Private method IListAddInfrastructure. For a description of this member, see Add.
Explicit interface implemetation Private method IListContainsInfrastructure. For a description of this member, see Contains.
Explicit interface implemetation Private method IListIndexOfInfrastructure. For a description of this member, see IndexOf.
Explicit interface implemetation Private method IListInsertInfrastructure. For a description of this member, see Insert.
Explicit interface implemetation Private property IListIsFixedSizeInfrastructure. For a description of this member, see IsFixedSize.
Explicit interface implemetation Private property IListItemInfrastructure. For a description of this member, see Item.
Explicit interface implemetation Private method IListRemoveInfrastructure. For a description of this member, see Remove.
Explicit interface implemetation Private property IStateManagerIsTrackingViewStateInfrastructure. For a description of this member, see IsTrackingViewState.
Explicit interface implemetation Private method IStateManagerLoadViewStateInfrastructure. Loads the previously saved state.
Explicit interface implemetation Private method IStateManagerSaveViewStateInfrastructure. Returns object containing state changes.
Explicit interface implemetation Private method IStateManagerTrackViewStateInfrastructure. Starts tracking state of changes.
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Remarks

The ListItemCollection class represents a collection of ListItem objects. The ListItem objects, in turn, represent the items displayed in list controls, such as the ListBox. To programmatically retrieve ListItem objects from a list control, use one of following methods:

  • Use the indexer to get a single ListItem from the collection, using array notation.

  • Use the CopyTo method to copy the contents of the collection to a SystemArray object, which can then be used to get items from the collection.

  • Use the GetEnumerator method to create a System.CollectionsIEnumerator implemented object, which can then be used to get items from the collection.

  • Use foreach (C#) or For Each (Visual Basic) to iterate through the collection.

The Count property specifies the total number of items in the collection, and is commonly used to determine the upper bound of the collection. You can add and remove items from the collection by using the Add and Remove methods.

Examples

The following code example demonstrates creating ListItemCollection objects, adding items to the collections, and removing items from the collections. In the example, the ListItemCollection named listBoxData is used as the data source for a ListBox control called ListBox1, and the ListItemCollection called ddBoxData is used as the data source for a DropDownList control called DropDownList1.

<%@ Page language="VB" AutoEventWireup="true" %>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
    Private Sub Page_Load(sender As Object, e As System.EventArgs) Handles MyBase.Load
        ' If this isn't the first time the page is loaded in this session,
        ' then don't recreate the DataTables.
        If Not IsPostBack Then
            ' Create a new ListItemCollection.
            Dim listBoxData As New ListItemCollection()
            ' Add items to the collection.
            listBoxData.Add(New ListItem("apples"))
            listBoxData.Add(New ListItem("bananas"))
            listBoxData.Add(New ListItem("cherries"))
            listBoxData.Add("grapes")
            listBoxData.Add("mangos")
            listBoxData.Add("oranges")
            ' Set the ListItemCollection as the data source for ListBox1.
            ListBox1.DataSource = listBoxData
            ListBox1.DataBind()

            ' Create a new ListItemCollection.
            Dim ddBoxData As New ListItemCollection()
            ' For now, just bind the data to the DropDownList.
            DropDownList1.DataSource = ddBoxData
            DropDownList1.DataBind()
        End If
    End Sub 'Page_Load

    Private Sub moveButton1_Click(sender As Object, e As System.EventArgs) 
        'Set the SelectedIndex to -1 so no items are selected.            
        ' The new item will be set as the selected item when it is added.
        DropDownList1.SelectedIndex = - 1
        ' Add the selected item to DropDownList1.
        DropDownList1.Items.Add(ListBox1.SelectedItem)
        ' Delete the selected item from ListBox1.
        ListBox1.Items.Remove(ListBox1.SelectedItem)
    End Sub 'moveButton1_Click


    Private Sub moveButton2_Click(sender As Object, e As System.EventArgs)
        'Set the SelectedIndex to -1 so no items are selected.
        ' The new item will be set as the selected item when it is added.
        ListBox1.SelectedIndex = - 1
        ' Add the selected item to ListBox1.
        ListBox1.Items.Add(DropDownList1.SelectedItem)
        'Delete the selected item from DropDownList1.
        DropDownList1.Items.Remove(DropDownList1.SelectedItem)
    End Sub 'moveButton2_Click
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
    <head>
    <title>ASP.NET Example</title>
</head>

    <body>
        <form id="form1" runat="server">
            <table cellpadding="6" border="0">
                <tr>
                    <td rowspan="2" valign="top">
                        <asp:ListBox id="ListBox1" runat="server" 
                            SelectionMode="Single" Width="100px">
                        </asp:ListBox>
                    </td>

                    <td>
                        <asp:Button id="moveButton1" runat="server" Text="Move -->"
                            Width="100px" OnClick="moveButton1_Click"></asp:Button>
                    </td>

                    <td rowspan="2" valign="top">
                        <asp:DropDownList Runat="server" ID="DropDownList1"
                            Width="100px">
                        </asp:DropDownList>
                    </td>
                </tr>

                <tr>
                    <td>
                        <asp:Button ID="moveButton2" Runat="server" Text="<-- Move"
                            Width="100px" onClick="moveButton2_Click"></asp:Button>
                    </td>
                </tr>
            </table>
        </form>
    </body>
</html>
<%@ Page language="C#" AutoEventWireup="true" %>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
    private void Page_Load(object sender, System.EventArgs e)
    {
        // If this isn't the first time the page is loaded in this session,
        // then don't recreate the DataTables.
        if (!IsPostBack)
        {
            // Create a new ListItemCollection.
            ListItemCollection listBoxData = new ListItemCollection();
            // Add items to the collection.
            listBoxData.Add(new ListItem("apples"));
            listBoxData.Add(new ListItem("bananas"));
            listBoxData.Add(new ListItem("cherries"));
            listBoxData.Add("grapes");
            listBoxData.Add("mangos");
            listBoxData.Add("oranges");
            // Set the ListItemCollection as the data source for ListBox1.
            ListBox1.DataSource = listBoxData;
            ListBox1.DataBind();

            // Create a new ListItemCollection.
            ListItemCollection ddBoxData = new ListItemCollection();
            // For now, just bind the data to the DropDownList.
            DropDownList1.DataSource = ddBoxData;
            DropDownList1.DataBind();
        }        
    }

    private void moveButton1_Click(object sender, System.EventArgs e)
    {
        //Set the SelectedIndex to -1 so no items are selected.
        // The new item will be set as the selected item when it is added.
        DropDownList1.SelectedIndex = -1;
        // Add the selected item to DropDownList1.
        DropDownList1.Items.Add(ListBox1.SelectedItem);
        // Delete the selected item from ListBox1.
        ListBox1.Items.Remove(ListBox1.SelectedItem);
    }

    private void moveButton2_Click(object sender, System.EventArgs e)
    {
        //Set the SelectedIndex to -1 so no items are selected.
        // The new item will be set as the selected item when it is added.
        ListBox1.SelectedIndex = -1;
        // Add the selected item to ListBox1.
        ListBox1.Items.Add(DropDownList1.SelectedItem);
        //Delete the selected item from DropDownList1.
        DropDownList1.Items.Remove(DropDownList1.SelectedItem);
    }
</script>
<html xmlns="http://www.w3.org/1999/xhtml" >
    <head>
    <title>ASP.NET Example</title>
</head>

    <body>
        <form id="form1" runat="server">
            <table cellpadding="6" border="0">
                <tr>
                    <td rowspan="2" valign="top">
                        <asp:ListBox id="ListBox1" runat="server" 
                            SelectionMode="Single" Width="100px">
                        </asp:ListBox>
                    </td>

                    <td>
                        <asp:Button id="moveButton1" runat="server" Text="Move -->"
                            Width="100px" OnClick="moveButton1_Click"></asp:Button>
                    </td>

                    <td rowspan="2" valign="top">
                        <asp:DropDownList Runat="server" ID="DropDownList1"
                            Width="100px">
                        </asp:DropDownList>
                    </td>
                </tr>

                <tr>
                    <td>
                        <asp:Button ID="moveButton2" Runat="server" Text="<-- Move"
                            Width="100px" onClick="moveButton2_Click"></asp:Button>
                    </td>
                </tr>
            </table>
        </form>
    </body>
</html>
<!-- This example demonstrates how to select multiple items from a DataList 
and add the selected items to a DataGrid. The example uses a For Each loop 
to iterate through the ListItem objects in the ListItemCollection of ListBox1. -->
<!-- This example demonstrates how to select multiple items from a DataList and add the 
selected items to a DataGrid. The example uses a foreach loop to iterate through 
the ListItem objects in the ListItemCollection of ListBox1. -->
<%@ Page language="VB" AutoEventWireup="true"%>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script runat="server">
            ' Global Variables.
            Private dv As DataView
            Private dt As New DataTable()

            Private Sub Page_Load(sender As Object, e As System.EventArgs)
                ' Set the number of rows displayed in the ListBox to be
                ' the number of items in the ListBoxCollection.
                ListBox1.Rows = ListBox1.Items.Count

                ' If the DataTable is already stored in the Web form's default
                ' HttpSessionState variable, then don't recreate the DataTable.
                If Session("data") Is Nothing Then
                    ' Add columns to the DataTable.
                    dt.Columns.Add(New DataColumn("Item"))
                    dt.Columns.Add(New DataColumn("Price"))
            ' Store the DataTable in the Session variable so it can be 
                    ' accessed again later.
                    Session("data") = dt

                    ' Use the table to create a DataView, because the DataGrid
                    ' can only bind to a data source that implements IEnumerable.
                    dv = New DataView(dt)

                    ' Set the DataView as the data source, and bind it to the DataGrid.
                    DataGrid1.DataSource = dv
                    DataGrid1.DataBind()
                End If
            End Sub

            Private Sub addButton_Click(sender As Object, e As System.EventArgs)
                ' Add the items selected in ListBox1 to DataGrid1.
                Dim item As ListItem
                For Each item In ListBox1.Items
                    If item.Selected Then
                        ' Add the item to the DataGrid.
                        ' First, get the DataTable from the Session variable.
                        dt = CType(Session("data"), DataTable)

                        If  Not (dt Is Nothing) Then
                            ' Create a new DataRow in the DataTable.
                            Dim dr As DataRow
                            dr = dt.NewRow()
                            ' Add the item to the new DataRow.
                            dr("Item") = item.Text
                            ' Add the item's value to the DataRow.
                            dr("Price") = item.Value
                            ' Add the DataRow to the DataTable.
                            dt.Rows.Add(dr)

                            ' Rebind the data to DataGrid1.
                            dv = new DataView(dt)
                            DataGrid1.DataSource = dv
                            DataGrid1.DataBind()
                        End If
                    End If
                Next item
            End Sub
        </script>
<html xmlns="http://www.w3.org/1999/xhtml" >
    <head>
    <title> ListItemCollection Example </title>
</head>

    <body>
        <form id="form1" runat="server">

            <h3> ListItemCollection Example </h3>

            <table cellpadding="6" border="0">
                <tr>
                    <td valign="top">
                        <asp:ListBox id="ListBox1" runat="server" SelectionMode="Multiple">
                            <asp:ListItem Value=".89">apples</asp:ListItem>
                            <asp:ListItem Value=".49">bananas</asp:ListItem>
                            <asp:ListItem Value="2.99">cherries</asp:ListItem>
                            <asp:ListItem Value="1.49">grapes</asp:ListItem>
                            <asp:ListItem Value="2.00">mangos</asp:ListItem>
                            <asp:ListItem Value="1.09">oranges</asp:ListItem>
                        </asp:ListBox>
                    </td>

                    <td valign="top">
                        <asp:Button id="addButton" runat="server" Text="Add -->"
                            Width="100px" OnClick="addButton_Click"></asp:Button>
                    </td>

                    <td valign="top">
                        <asp:DataGrid Runat="server" ID="DataGrid1" CellPadding="4">
                        </asp:DataGrid>
                    </td>
                </tr>
            </table>        
        </form>
    </body>
</html>
<%@ Page language="c#" AutoEventWireup="true"%>
<%@ Import Namespace="System.Data" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
    "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<script language="C#" runat="server">
            // Global Variables.
            private DataView dv;
            private DataTable dt = new DataTable();

            private void Page_Load(object sender, System.EventArgs e)
            {
                // Set the number of rows displayed in the ListBox to be
                // the number of items in the ListBoxCollection.
                ListBox1.Rows = ListBox1.Items.Count;

                // If the DataTable is already stored in the Web form's default
                // HttpSessionState variable, then don't recreate the DataTable.
                if (Session["data"] == null)
                {
                    // Add columns to the DataTable.
                    dt.Columns.Add(new DataColumn("Item"));
                    dt.Columns.Add(new DataColumn("Price"));
            // Store the DataTable in the Session variable so it can 
                    // be accessed again later.
                    Session["data"] = dt;

                    // Use the table to create a DataView, because the DataGrid
                    // can only bind to a data source that implements IEnumerable.
                    dv = new DataView(dt);

                    // Set the DataView as the data source, and bind it to the DataGrid.
                    DataGrid1.DataSource = dv;
                    DataGrid1.DataBind();
                }
            }

            private void addButton_Click(object sender, System.EventArgs e)
            {
                // Add the items selected in ListBox1 to DataGrid1.
                foreach (ListItem item in ListBox1.Items)
                {
                    if (item.Selected)
                    {
                        // Add the item to the DataGrid.
                        // First, get the DataTable from the Session variable.
                        dt = (DataTable)Session["data"];

                        if (dt != null)
                        { 
                            // Create a new DataRow in the DataTable.
                            DataRow dr = dt.NewRow();
                            // Add the item to the new DataRow.
                            dr["Item"] = item.Text;
                            // Add the item's value to the DataRow.
                            dr["Price"] = item.Value;
                            // Add the DataRow to the DataTable.
                            dt.Rows.Add(dr);

                            // Rebind the data to DataGrid1.
                            dv = new DataView(dt);
                            DataGrid1.DataSource = dv;
                            DataGrid1.DataBind();
                        }
                    }
                }
            }
        </script>
<html xmlns="http://www.w3.org/1999/xhtml" >
    <head>
    <title> ListItemCollection Example </title>
</head>

    <body>
        <form id="form1" runat="server">

            <h3> ListItemCollection Example </h3>

            <table cellpadding="6" border="0">
                <tr>
                    <td valign="top">
                        <asp:ListBox id="ListBox1" runat="server" SelectionMode="Multiple">
                            <asp:ListItem Value=".89">apples</asp:ListItem>
                            <asp:ListItem Value=".49">bananas</asp:ListItem>
                            <asp:ListItem Value="2.99">cherries</asp:ListItem>
                            <asp:ListItem Value="1.49">grapes</asp:ListItem>
                            <asp:ListItem Value="2.00">mangos</asp:ListItem>
                            <asp:ListItem Value="1.09">oranges</asp:ListItem>
                        </asp:ListBox>
                    </td>

                    <td valign="top">
                        <asp:Button id="addButton" runat="server" Text="Add -->"
                            Width="100px" OnClick="addButton_Click"></asp:Button>
                    </td>

                    <td valign="top">
                        <asp:DataGrid Runat="server" ID="DataGrid1" CellPadding="4">
                        </asp:DataGrid>
                    </td>
                </tr>
            </table>        
        </form>
    </body>
</html>
Version Information

.NET Framework

Supported in: 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0
Platforms

Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

Thread Safety
Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.