Dictionary(Of TKey, TValue).ICollection(Of KeyValuePair(Of TKey, TValue)).Contains Method
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
Determines whether the ICollection(Of T) contains a specific key and value.
Assembly: mscorlib (in mscorlib.dll)
'Declaration Private Function Contains ( _ keyValuePair As KeyValuePair(Of TKey, TValue) _ ) As Boolean Implements ICollection(Of KeyValuePair(Of TKey, TValue)).Contains
Parameters
- keyValuePair
- Type: System.Collections.Generic.KeyValuePair(Of TKey, TValue)
The KeyValuePair(Of TKey, TValue) structure to locate in the ICollection(Of T).
Return Value
Type: System.Booleantrue if keyValuePair is found in the ICollection(Of T); otherwise, false.
Implements
ICollection(Of T).Contains(T)This method determines equality using the default equality comparer EqualityComparer(Of T).Default for the System.Collections.Generic.KeyValuePair(Of TKey, TValue) structure.
This method approaches an O(1) operation.
The following example shows how to use explicit interface implementations of the System.Collections.Generic.ICollection(Of T) generic interface to manipulate a Dictionary(Of TKey, TValue) object.
Imports System.Collections.Generic Public Class Example Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) ' Create a new dictionary of strings, with string keys, and ' access it through the generic ICollection interface. The ' generic ICollection interface views the dictionary as a ' collection of KeyValuePair objects with the same type ' arguments as the dictionary. ' Dim openWith As ICollection(Of KeyValuePair(Of String, String)) _ = New Dictionary(Of String, String) ' Add some elements to the dictionary. When elements are ' added through the ICollection(Of T) interface, the keys ' and values must be wrapped in KeyValuePair objects. ' openWith.Add(New KeyValuePair(Of String, String)("txt", "notepad.exe")) openWith.Add(New KeyValuePair(Of String, String)("bmp", "paint.exe")) openWith.Add(New KeyValuePair(Of String, String)("dib", "paint.exe")) openWith.Add(New KeyValuePair(Of String, String)("rtf", "wordpad.exe")) outputBlock.Text &= vbCrLf For Each element As KeyValuePair(Of String, String) In openWith outputBlock.Text &= String.Format("{0}, {1}", element.Key, element.Value) & vbCrLf Next ' The Contains method also takes a KeyValuePair object. ' outputBlock.Text &= String.Format(vbLf & _ "Contains(KeyValuePair(""txt"", ""notepad.exe"")): {0}", _ openWith.Contains(New KeyValuePair(Of String, String)("txt", "notepad.exe"))) & vbCrLf ' The Remove method takes a KeyValuePair object.) ' ' Use the Remove method to remove a key/value pair. outputBlock.Text &= String.Format(vbLf & _ "Remove(New KeyValuePair(""dib"", ""paint.exe""))") & vbCrLf openWith.Remove(New KeyValuePair(Of String, String)("dib", "paint.exe")) outputBlock.Text &= vbCrLf For Each element As KeyValuePair(Of String, String) In openWith outputBlock.Text &= String.Format("{0}, {1}", element.Key, element.Value) & vbCrLf Next ' Create an array of KeyValuePair objects and copy the ' contents of the dictionary to it. Subtract one from the ' array size because Visual Basic allocates an extra array ' element. Dim copy(openWith.Count - 1) As KeyValuePair(Of String, String) openWith.CopyTo(copy, 0) ' List the contents of the array. ' outputBlock.Text &= vbCrLf For Each element As KeyValuePair(Of String, String) In copy outputBlock.Text &= String.Format("{0}, {1}", element.Key, element.Value) & vbCrLf Next End Sub End Class ' This code example produces the following output: ' 'txt, notepad.exe 'bmp, paint.exe 'dib, paint.exe 'rtf, wordpad.exe ' 'Contains(KeyValuePair("txt", "notepad.exe")): True ' 'Remove(New KeyValuePair("dib", "paint.exe")) ' 'txt, notepad.exe 'bmp, paint.exe 'rtf, wordpad.exe ' 'txt, notepad.exe 'bmp, paint.exe 'rtf, wordpad.exe