List<T> Constructor
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Initializes a new instance of the List<T> class that is empty and has the default initial capacity.
Namespace: System.Collections.Generic
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Public Sub New
public List()
Remarks
The capacity of a List<T> is the number of elements that the List<T> can hold. As elements are added to a List<T>, the capacity is automatically increased as required by reallocating the internal array.
If the size of the collection can be estimated, using the List<T>(Int32) constructor and specifying the initial capacity eliminates the need to perform a number of resizing operations while adding elements to the List<T>.
The capacity can be decreased by calling the TrimExcess method or by setting the Capacity property explicitly. Decreasing the capacity reallocates memory and copies all the elements in the List<T>.
This constructor is an O(1) operation.
Examples
The following code example demonstrates the default constructor of the List<T> generic class. The default constructor creates a list with the default capacity, as demonstrated by displaying the Capacity property.
The code example adds, inserts, and removes items, showing how the capacity changes as these methods are used.
Imports System.Collections.Generic
Public Class Example
Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock)
Dim dinosaurs As New List(Of String)
outputBlock.Text &= String.Format(vbLf & "Capacity: {0}", dinosaurs.Capacity) & vbCrLf
dinosaurs.Add("Tyrannosaurus")
dinosaurs.Add("Amargasaurus")
dinosaurs.Add("Mamenchisaurus")
dinosaurs.Add("Deinonychus")
dinosaurs.Add("Compsognathus")
outputBlock.Text &= vbCrLf
For Each dinosaur As String In dinosaurs
outputBlock.Text &= dinosaur & vbCrLf
Next
outputBlock.Text &= String.Format(vbLf & "Capacity: {0}", dinosaurs.Capacity) & vbCrLf
outputBlock.Text &= String.Format("Count: {0}", dinosaurs.Count) & vbCrLf
outputBlock.Text &= vbLf & String.Format("Contains(""Deinonychus"": {0}", _
dinosaurs.Contains("Deinonychus")) & vbCrLf
outputBlock.Text &= String.Format(vbLf & "Insert(2, ""Compsognathus"")") & vbCrLf
dinosaurs.Insert(2, "Compsognathus")
outputBlock.Text &= vbCrLf
For Each dinosaur As String In dinosaurs
outputBlock.Text &= dinosaur & vbCrLf
Next
outputBlock.Text &= String.Format(vbLf & "dinosaurs(3): {0}", dinosaurs(3)) & vbCrLf
outputBlock.Text &= vbLf & "Remove(""Compsognathus"")" & vbCrLf
dinosaurs.Remove("Compsognathus")
outputBlock.Text &= vbCrLf
For Each dinosaur As String In dinosaurs
outputBlock.Text &= dinosaur & vbCrLf
Next
dinosaurs.TrimExcess()
outputBlock.Text &= vbLf & "TrimExcess()" & vbCrLf
outputBlock.Text &= String.Format("Capacity: {0}", dinosaurs.Capacity) & vbCrLf
outputBlock.Text &= String.Format("Count: {0}", dinosaurs.Count) & vbCrLf
dinosaurs.Clear()
outputBlock.Text &= vbLf & "Clear()" & vbCrLf
outputBlock.Text &= String.Format("Capacity: {0}", dinosaurs.Capacity) & vbCrLf
outputBlock.Text &= String.Format("Count: {0}", dinosaurs.Count) & vbCrLf
End Sub
End Class
' This code example produces the following output:
'
'Capacity: 0
'
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Deinonychus
'Compsognathus
'
'Capacity: 8
'Count: 5
'
'Contains("Deinonychus"): True
'
'Insert(2, "Compsognathus")
'
'Tyrannosaurus
'Amargasaurus
'Compsognathus
'Mamenchisaurus
'Deinonychus
'Compsognathus
'
'dinosaurs(3): Mamenchisaurus
'
'Remove("Compsognathus")
'
'Tyrannosaurus
'Amargasaurus
'Mamenchisaurus
'Deinonychus
'Compsognathus
'
'TrimExcess()
'Capacity: 5
'Count: 5
'
'Clear()
'Capacity: 5
'Count: 0
using System;
using System.Collections.Generic;
public class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
List<string> dinosaurs = new List<string>();
outputBlock.Text += String.Format("\nCapacity: {0}", dinosaurs.Capacity) + "\n";
dinosaurs.Add("Tyrannosaurus");
dinosaurs.Add("Amargasaurus");
dinosaurs.Add("Mamenchisaurus");
dinosaurs.Add("Deinonychus");
dinosaurs.Add("Compsognathus");
outputBlock.Text += "\n";
foreach (string dinosaur in dinosaurs)
{
outputBlock.Text += dinosaur + "\n";
}
outputBlock.Text += String.Format("\nCapacity: {0}", dinosaurs.Capacity) + "\n";
outputBlock.Text += String.Format("Count: {0}", dinosaurs.Count) + "\n";
outputBlock.Text += String.Format("\nContains(\"Deinonychus\"): {0}",
dinosaurs.Contains("Deinonychus")) + "\n";
outputBlock.Text += String.Format("\nInsert(2, \"Compsognathus\")") + "\n";
dinosaurs.Insert(2, "Compsognathus");
outputBlock.Text += "\n";
foreach (string dinosaur in dinosaurs)
{
outputBlock.Text += dinosaur + "\n";
}
outputBlock.Text += String.Format("\ndinosaurs[3]: {0}", dinosaurs[3]) + "\n";
outputBlock.Text += "\nRemove(\"Compsognathus\")" + "\n";
dinosaurs.Remove("Compsognathus");
outputBlock.Text += "\n";
foreach (string dinosaur in dinosaurs)
{
outputBlock.Text += dinosaur + "\n";
}
dinosaurs.TrimExcess();
outputBlock.Text += "\nTrimExcess()" + "\n";
outputBlock.Text += String.Format("Capacity: {0}", dinosaurs.Capacity) + "\n";
outputBlock.Text += String.Format("Count: {0}", dinosaurs.Count) + "\n";
dinosaurs.Clear();
outputBlock.Text += "\nClear()" + "\n";
outputBlock.Text += String.Format("Capacity: {0}", dinosaurs.Capacity) + "\n";
outputBlock.Text += String.Format("Count: {0}", dinosaurs.Count) + "\n";
}
}
/* This code example produces the following output:
Capacity: 0
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus
Capacity: 8
Count: 5
Contains("Deinonychus"): True
Insert(2, "Compsognathus")
Tyrannosaurus
Amargasaurus
Compsognathus
Mamenchisaurus
Deinonychus
Compsognathus
dinosaurs[3]: Mamenchisaurus
Remove("Compsognathus")
Tyrannosaurus
Amargasaurus
Mamenchisaurus
Deinonychus
Compsognathus
TrimExcess()
Capacity: 5
Count: 5
Clear()
Capacity: 5
Count: 0
*/
Version Information
Silverlight
Supported in: 5, 4, 3
Silverlight for Windows Phone
Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0
XNA Framework
Supported in: Xbox 360, Windows Phone OS 7.0
Platforms
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.