ListDictionary.Contains(Object) Methode

Definition

Namespace:
System.Collections.Specialized
Assemblys:
System.dll, System.Collections.Specialized.dll
Assembly:
System.dll
Assembly:
netstandard.dll

Bestimmt, ob die ListDictionary einen bestimmten Schlüssel enthält.

public:
 virtual bool Contains(System::Object ^ key);
public bool Contains(object key);
abstract member Contains : obj -> bool
override this.Contains : obj -> bool
Public Function Contains (key As Object) As Boolean

Parameter

key
Object

Der Schlüssel, der in der ListDictionaryDatei gefunden werden soll.

Gibt zurück

Boolean

true wenn der ListDictionary Eintrag mit dem angegebenen Schlüssel enthalten ist; andernfalls false.

Implementiert

Contains(Object)

Ausnahmen

ArgumentNullException

key ist null.

Beispiele

Im folgenden Codebeispiel wird nach einem Element in einem ListDictionary.

using System;
using System.Collections;
using System.Collections.Specialized;

public class SamplesListDictionary  {

   public static void Main()  {

      // Creates and initializes a new ListDictionary.
      ListDictionary myCol = new ListDictionary();
      myCol.Add( "Braeburn Apples", "1.49" );
      myCol.Add( "Fuji Apples", "1.29" );
      myCol.Add( "Gala Apples", "1.49" );
      myCol.Add( "Golden Delicious Apples", "1.29" );
      myCol.Add( "Granny Smith Apples", "0.89" );
      myCol.Add( "Red Delicious Apples", "0.99" );

      // Displays the values in the ListDictionary in three different ways.
      Console.WriteLine( "Initial contents of the ListDictionary:" );
      PrintKeysAndValues( myCol );

      // Searches for a key.
      if ( myCol.Contains( "Kiwis" ) )
         Console.WriteLine( "The collection contains the key \"Kiwis\"." );
      else
         Console.WriteLine( "The collection does not contain the key \"Kiwis\"." );
      Console.WriteLine();
   }

   public static void PrintKeysAndValues( IDictionary myCol )  {
      Console.WriteLine( "   KEY                       VALUE" );
      foreach ( DictionaryEntry de in myCol )
         Console.WriteLine( "   {0,-25} {1}", de.Key, de.Value );
      Console.WriteLine();
   }
}


/*
This code produces the following output.

Initial contents of the ListDictionary:
   KEY                       VALUE
   Braeburn Apples           1.49
   Fuji Apples               1.29
   Gala Apples               1.49
   Golden Delicious Apples   1.29
   Granny Smith Apples       0.89
   Red Delicious Apples      0.99

The collection does not contain the key "Kiwis".

*/

Imports System.Collections
Imports System.Collections.Specialized

Public Class SamplesListDictionary   

   Public Shared Sub Main()

      ' Creates and initializes a new ListDictionary.
      Dim myCol As New ListDictionary()
      myCol.Add("Braeburn Apples", "1.49")
      myCol.Add("Fuji Apples", "1.29")
      myCol.Add("Gala Apples", "1.49")
      myCol.Add("Golden Delicious Apples", "1.29")
      myCol.Add("Granny Smith Apples", "0.89")
      myCol.Add("Red Delicious Apples", "0.99")

      ' Displays the values in the ListDictionary in three different ways.
      Console.WriteLine("Initial contents of the ListDictionary:")
      PrintKeysAndValues(myCol)

      ' Searches for a key.
      If myCol.Contains("Kiwis") Then
         Console.WriteLine("The collection contains the key ""Kiwis"".")
      Else
         Console.WriteLine("The collection does not contain the key ""Kiwis"".")
      End If
      Console.WriteLine()

   End Sub

   Public Shared Sub PrintKeysAndValues(myCol As IDictionary)

      Console.WriteLine("   KEY                       VALUE")
      Dim de As DictionaryEntry
      For Each de In  myCol
         Console.WriteLine("   {0,-25} {1}", de.Key, de.Value)
      Next de
      Console.WriteLine()

   End Sub

End Class


'This code produces the following output.
'
'Initial contents of the ListDictionary:
'   KEY                       VALUE
'   Braeburn Apples           1.49
'   Fuji Apples               1.29
'   Gala Apples               1.49
'   Golden Delicious Apples   1.29
'   Granny Smith Apples       0.89
'   Red Delicious Apples      0.99
'
'The collection does not contain the key "Kiwis".

Hinweise

Bei dieser Methode handelt es sich um einen O()-Vorgang, wobei n es sich um einen O(n)-Vorgang handeltCount.

Diese Methode verwendet die Objekte Equals und CompareTo Methoden key der Auflistung, um zu bestimmen, ob item vorhanden ist.

Gilt für:

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