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Collection(Of T) Constructor

Initializes a new instance of the Collection(Of T) class that is empty.

Namespace:  System.Collections.ObjectModel
Assembly:  mscorlib (in mscorlib.dll)

'Declaration
Public Sub New

This constructor is an O(1) operation.

The following code example demonstrates many of the properties and methods of Collection(Of T). The code example creates a collection of strings with the Collection(Of T) constructor, uses the Add method to add several strings, displays the Count, and lists the strings. The example uses the IndexOf method to find the index of a string and the Contains method to determine whether a string is in the collection. The example inserts a string using the Insert method and retrieves and sets strings using the default Item property (the indexer in C#). The example removes strings by string identity using the Remove method and by index using the RemoveAt method. Finally, the Clear method is used to clear all strings from the collection.

Imports System
Imports System.Collections.Generic
Imports System.Collections.ObjectModel

Public Class Demo

    Public Shared Sub Main() 

        Dim dinosaurs As New Collection(Of String)

        dinosaurs.Add("Psitticosaurus")
        dinosaurs.Add("Caudipteryx")
        dinosaurs.Add("Compsognathus")
        dinosaurs.Add("Muttaburrasaurus")

        Console.WriteLine("{0} dinosaurs:", dinosaurs.Count)
        Display(dinosaurs)

        Console.WriteLine(vbLf & "IndexOf(""Muttaburrasaurus""): {0}", _
            dinosaurs.IndexOf("Muttaburrasaurus"))

        Console.WriteLine(vbLf & "Contains(""Caudipteryx""): {0}", _
            dinosaurs.Contains("Caudipteryx"))

        Console.WriteLine(vbLf & "Insert(2, ""Nanotyrannus"")")
        dinosaurs.Insert(2, "Nanotyrannus")
        Display(dinosaurs)

        Console.WriteLine(vbLf & "dinosaurs(2): {0}", dinosaurs(2))

        Console.WriteLine(vbLf & "dinosaurs(2) = ""Microraptor""")
        dinosaurs(2) = "Microraptor"
        Display(dinosaurs)

        Console.WriteLine(vbLf & "Remove(""Microraptor"")")
        dinosaurs.Remove("Microraptor")
        Display(dinosaurs)

        Console.WriteLine(vbLf & "RemoveAt(0)")
        dinosaurs.RemoveAt(0)
        Display(dinosaurs)

        Console.WriteLine(vbLf & "dinosaurs.Clear()")
        dinosaurs.Clear()
        Console.WriteLine("Count: {0}", dinosaurs.Count)

    End Sub 

    Private Shared Sub Display(ByVal cs As Collection(Of String)) 
        Console.WriteLine()
        For Each item As String In cs
            Console.WriteLine(item)
        Next item
    End Sub 
End Class 

' This code example produces the following output: 

'4 dinosaurs: 

'Psitticosaurus 
'Caudipteryx 
'Compsognathus 
'Muttaburrasaurus 

'IndexOf("Muttaburrasaurus"): 3 

'Contains("Caudipteryx"): True 

'Insert(2, "Nanotyrannus") 

'Psitticosaurus 
'Caudipteryx 
'Nanotyrannus 
'Compsognathus 
'Muttaburrasaurus 

'dinosaurs(2): Nanotyrannus 

'dinosaurs(2) = "Microraptor" 

'Psitticosaurus 
'Caudipteryx 
'Microraptor 
'Compsognathus 
'Muttaburrasaurus 

'Remove("Microraptor") 

'Psitticosaurus 
'Caudipteryx 
'Compsognathus 
'Muttaburrasaurus 

'RemoveAt(0) 

'Caudipteryx 
'Compsognathus 
'Muttaburrasaurus 

'dinosaurs.Clear() 
'Count: 0

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Portable Class Library

Supported in: Portable Class Library
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