Dictionary<TKey,TValue>.IDictionary.Contains(Object) Método

Definição

Namespace:

System.Collections.Generic

Assembly:

System.Collections.dll

Assembly:

mscorlib.dll

Assembly:

netstandard.dll

Determina se o IDictionary contém um elemento com a chave especificada.

 virtual bool System.Collections.IDictionary.Contains(System::Object ^ key) = System::Collections::IDictionary::Contains;

bool IDictionary.Contains (object key);

abstract member System.Collections.IDictionary.Contains : obj -> bool
override this.System.Collections.IDictionary.Contains : obj -> bool

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

Parâmetros

key

Object

A chave a ser localizada no IDictionary.

Retornos

Boolean

true se o IDictionary contiver um elemento com a chave especificada; caso contrário, false.

Implementações

Contains(Object)

Exceções

ArgumentNullException

key é null.

Exemplos

O exemplo de código a seguir mostra como usar o IDictionary.Contains método da System.Collections.IDictionary interface com um Dictionary<TKey,TValue>. O exemplo demonstra que o método retorna false se uma chave do tipo de dados errado for fornecida.

O exemplo de código faz parte de um exemplo maior, inclusive saída, fornecido para o método IDictionary.Add.

using System;
using System.Collections;
using System.Collections.Generic;

public class Example
{
    public static void Main()
    {
        // Create a new dictionary of strings, with string keys,
        // and access it using the IDictionary interface.
        //
        IDictionary openWith = new Dictionary<string, string>();

        // Add some elements to the dictionary. 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");

Imports System.Collections
Imports System.Collections.Generic

Public Class Example
    
    Public Shared Sub Main() 

        ' Create a new dictionary of strings, with string keys,
        ' and access it using the IDictionary interface.
        '
        Dim openWith As IDictionary = _
            New Dictionary(Of String, String)
        
        ' Add some elements to the dictionary. 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 (!openWith.Contains("ht"))
{
    openWith.Add("ht", "hypertrm.exe");
    Console.WriteLine("Value added for key = \"ht\": {0}",
        openWith["ht"]);
}

// IDictionary.Contains returns false if the wrong data
// type is supplied.
Console.WriteLine("openWith.Contains(29.7) returns {0}",
    openWith.Contains(29.7));

' 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}", _
        openWith("ht"))
End If

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

    }
}

    End Sub

End Class

Comentários

Esse método retorna false se key for de um tipo que não é atribuível ao tipo TKey de chave do Dictionary<TKey,TValue>.

Este método abrange uma operação O(1).