Adds a member to a Collection object.

Public Sub Add( _
   ByVal Item As Object, _
   Optional ByVal Key As String, _
   Optional ByVal { Before | After } As Object = Nothing _
)

Parameters

Item

Required. An object of any type that specifies the member to add to the collection.

Key

Optional. A unique String expression that specifies a key string that can be used instead of a positional index to access a member of the collection.

Before

Optional. An expression that specifies a relative position in the collection. The member to be added is placed in the collection before the member identified by the Before argument. If Before is a numeric expression, it must be a number from 1 to the value of the collection's Count property. If Before is a String expression, it must correspond to the key string specified when the member being referred to was added to the collection. You cannot specify both Before and After.

After

Optional. An expression that specifies a relative position in the collection. The member to be added is placed in the collection after the member identified by the After argument. If After is a numeric expression, it must be a number from 1 to the value of the collection's Count property. If After is a String expression, it must correspond to the key string specified when the member referred to was added to the collection. You cannot specify both Before and After.

Exceptions/Error Codes

Remarks

The Before or After argument must refer to an existing member of the collection; otherwise, an error occurs.

An error also occurs if a specified Key value matches the key for an existing member of the collection.

Example

This example uses the Add method to add Child objects — instances of a class called Child containing a Public property Name — to a collection called Family. To see how this works, create a Form with two Buttons and set their Text properties to Add and List. Add the Child class definition and the Family declaration to the form code. Modify the Click events for the Add and List buttons as shown. The Add button allows you to add children. The List button will display the names of all the children.

Public Class Child
   Public Name As String
   Sub New(ByVal newName As String)
      Name = newName
   End Sub
End Class

Private family As New Collection() ' Create a Collection object.

Private Sub AddChild_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button1.Click
   Dim newName As String
   newName = InputBox("Name of new family member: ")
   If newName <> "" Then
      family.Add(New Child(newName), newName)
   End If
End Sub

Private Sub ListChild_Click(ByVal sender As System.Object, _
ByVal e As System.EventArgs) Handles Button2.Click
   Dim aChild As Child
   For Each aChild In family
      MsgBox(aChild.Name)
   Next
End Sub

Requirements

Namespace: Microsoft.VisualBasic

Module: Collection

Assembly: Microsoft Visual Basic .NET Runtime (in Microsoft.VisualBasic.dll)

See Also

Item Property | Remove Method | ArgumentException Class

Applies To

Collection Object