ComboBox.ObjectCollection.System.Collections.IList.Add Method

This method supports the .NET Framework infrastructure and is not intended to be used directly from your code.

For a description of this member, see IList.Add.

Namespace: System.Windows.Forms
Assembly: System.Windows.Forms (in

int IList.Add (
	Object item
J# supports the use of explicit interface implementations, but not the declaration of new ones.
JScript supports the use of explicit interface implementations, but not the declarations of new ones.



An object that represents the item to add to the collection.

Return Value

The zero-based index of the item in the collection.

Exception typeCondition


The item parameter is a null reference (Nothing in Visual Basic).


There is insufficient space available to store the new item.

This member is an explicit interface member implementation. It can be used only when the ComboBox.ObjectCollection instance is cast to an IList interface.

This method adds an item to the combo box. If the Sorted property of the ComboBox is set to true, the item is inserted into the list alphabetically. Otherwise, the item is inserted at the end of the list.

A visual representation of the item is displayed in the combo box. This content representation is specified by the DisplayMember property. If the DisplayMember property is a null reference (Nothing in Visual Basic), the item's ToString method is called to obtain the string that is displayed in the combo box; otherwise, the property of the stored object as specified by the DisplayMember property is displayed. To add a set of items to the combo box, it is best to use the AddRange method. If you choose to use the Add method to add a set of items to the combo box, use the BeginUpdate method to suspend repainting during your add and the EndUpdate method to resume repainting. You can use the Insert method to specify the location in the list where an item is added. When an object is added to the collection, the ComboBox calls the object's ToString method to obtain the string to display in the list.

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

.NET Framework

Supported in: 2.0, 1.1, 1.0

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