List(Of T).Contains Method
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Determines whether an element is in the List(Of T).
Assembly: mscorlib (in mscorlib.dll)
Parameters
- item
- Type: T
The object to locate in the List(Of T). The value can be Nothing for reference types.
Implements
ICollection(Of T).Contains(T)This method determines equality using the default equality comparer EqualityComparer(Of T).Default for T, the type of values in the list.
This method performs a linear search; therefore, this method is an O(n) operation, where n is Count.
The following code example demonstrates the Contains method and various other properties and methods of the List(Of T) generic class. After the list has been populated, the Contains method is used to search for an item.
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