Dictionary<TKey, TValue>.ICollection<KeyValuePair<TKey, TValue>>.Contains Method
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Determines whether the ICollection<T> contains a specific key and value.
Namespace: System.Collections.Generic
Assembly: mscorlib (in mscorlib.dll)
Syntax
'Declaration
Private Function Contains ( _
keyValuePair As KeyValuePair(Of TKey, TValue) _
) As Boolean Implements ICollection(Of KeyValuePair(Of TKey, TValue)).Contains
bool ICollection<KeyValuePair<TKey, TValue>>.Contains(
KeyValuePair<TKey, TValue> keyValuePair
)
Parameters
- keyValuePair
Type: System.Collections.Generic.KeyValuePair<TKey, TValue>
The KeyValuePair<TKey, TValue> structure to locate in the ICollection<T>.
Return Value
Type: System.Boolean
true if keyValuePair is found in the ICollection<T>; otherwise, false.
Implements
Remarks
This method determines equality using the default equality comparer EqualityComparer<T>.Default for the System.Collections.Generic.KeyValuePair<TKey, TValue> structure.
This method approaches an O(1) operation.
Examples
The following example shows how to use explicit interface implementations of the System.Collections.Generic.ICollection<T> generic interface to manipulate a Dictionary<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
using System;
using System.Collections.Generic;
public class Example
{
public static void Demo(System.Windows.Controls.TextBlock outputBlock)
{
// 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.
//
ICollection<KeyValuePair<String, String>> openWith =
new Dictionary<String, String>();
// Add some elements to the dictionary. When elements are
// added through the ICollection<T> interface, the keys
// and values must be wrapped in KeyValuePair objects.
//
openWith.Add(new KeyValuePair<String, String>("txt", "notepad.exe"));
openWith.Add(new KeyValuePair<String, String>("bmp", "paint.exe"));
openWith.Add(new KeyValuePair<String, String>("dib", "paint.exe"));
openWith.Add(new KeyValuePair<String, String>("rtf", "wordpad.exe"));
outputBlock.Text += "\n";
foreach (KeyValuePair<string, string> element in openWith)
{
outputBlock.Text += String.Format("{0}, {1}", element.Key, element.Value) + "\n";
}
// The Contains method also takes a KeyValuePair object.
//
outputBlock.Text += String.Format(
"\nContains(KeyValuePair(\"txt\", \"notepad.exe\")): {0}",
openWith.Contains(new KeyValuePair<String, String>("txt", "notepad.exe"))) + "\n";
// The Remove method takes a KeyValuePair object.)
//
// Use the Remove method to remove a key/value pair.
outputBlock.Text += String.Format("\nRemove(new KeyValuePair(\"dib\", \"paint.exe\"))") + "\n";
openWith.Remove(new KeyValuePair<String, String>("dib", "paint.exe"));
outputBlock.Text += "\n";
foreach (KeyValuePair<string, string> element in openWith)
{
outputBlock.Text += String.Format("{0}, {1}", element.Key, element.Value) + "\n";
}
// Create an array of KeyValuePair objects and copy the
// contents of the dictionary to it.
//
KeyValuePair<string, string>[] copy =
new KeyValuePair<string, string>[openWith.Count];
openWith.CopyTo(copy, 0);
// List the contents of the array.
//
outputBlock.Text += "\n";
foreach (KeyValuePair<string, string> element in copy)
{
outputBlock.Text += String.Format("{0}, {1}", element.Key, element.Value) + "\n";
}
}
}
/* 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
*/
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.