SortedList(Of TKey, TValue).IDictionary.Contains Method (Object)


Determines whether the IDictionary contains an element with the specified key.

Namespace:   System.Collections.Generic
Assembly:  System (in System.dll)

Private Function Contains (
	key As Object
) As Boolean
	Implements IDictionary.Contains


Type: System.Object

The key to locate in the IDictionary.

Return Value

Type: System.Boolean

true if the IDictionary contains an element with the key; otherwise, false.

Exception Condition

key is null.

This method returns false if key is of a type that is not assignable to the key type TKey of the SortedList(Of TKey, TValue).

This method is an O(log n) operation, where n is Count.

The following code example shows how to use the IDictionary.Contains method of the System.Collections.IDictionary interface with a SortedList(Of TKey, TValue). The example demonstrates that the method returns false if a key of the wrong data type is supplied.

The code example is part of a larger example, including output, provided for the IDictionary.Add method.

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

Public Class Example

    Public Shared Sub Main() 

        ' Create a new sorted list of strings, with string keys,
        ' and access it using the IDictionary interface.
        Dim openWith As IDictionary = _
            New sortedList(Of String, String)

        ' Add some elements to the sorted list. There are no 
        ' duplicate keys, but some of the values are duplicates.
        ' IDictionary.Add throws an exception if incorrect types
        ' are supplied for key or value.
        openWith.Add("txt", "notepad.exe")
        openWith.Add("bmp", "paint.exe")
        openWith.Add("dib", "paint.exe")
        openWith.Add("rtf", "wordpad.exe")
' Contains can be used to test keys before inserting 
' them.
If Not openWith.Contains("ht") Then
    openWith.Add("ht", "hypertrm.exe")
    Console.WriteLine("Value added for key = ""ht"": {0}", _
End If

' IDictionary.Contains returns False if the wrong data 
' type is supplied.
Console.WriteLine("openWith.Contains(29.7) returns {0}", _

    End Sub

End Class

Universal Windows Platform
Available since 10
.NET Framework
Available since 2.0
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