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HybridDictionary.GetEnumerator Methode

Definition

Gibt einen IDictionaryEnumerator zurück, der HybridDictionary durchläuft.

public:
 virtual System::Collections::IDictionaryEnumerator ^ GetEnumerator();
public System.Collections.IDictionaryEnumerator GetEnumerator ();
abstract member GetEnumerator : unit -> System.Collections.IDictionaryEnumerator
override this.GetEnumerator : unit -> System.Collections.IDictionaryEnumerator
Public Function GetEnumerator () As IDictionaryEnumerator

Gibt zurück

Ein IDictionaryEnumerator für das HybridDictionary.

Implementiert

Beispiele

Im folgenden Codebeispiel werden die Elemente eines HybridDictionaryaufgelistet.

#using <System.dll>

using namespace System;
using namespace System::Collections;
using namespace System::Collections::Specialized;

void PrintKeysAndValues1( IDictionary^ myCol );
void PrintKeysAndValues2( IDictionary^ myCol );
void PrintKeysAndValues3( HybridDictionary^ myCol );

int main()
{
   // Creates and initializes a new HybridDictionary.
   HybridDictionary^ myCol = gcnew HybridDictionary;
   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" );
   myCol->Add( "Plantain Bananas", "1.49" );
   myCol->Add( "Yellow Bananas", "0.79" );
   myCol->Add( "Strawberries", "3.33" );
   myCol->Add( "Cranberries", "5.98" );
   myCol->Add( "Navel Oranges", "1.29" );
   myCol->Add( "Grapes", "1.99" );
   myCol->Add( "Honeydew Melon", "0.59" );
   myCol->Add( "Seedless Watermelon", "0.49" );
   myCol->Add( "Pineapple", "1.49" );
   myCol->Add( "Nectarine", "1.99" );
   myCol->Add( "Plums", "1.69" );
   myCol->Add( "Peaches", "1.99" );

   // Display the contents of the collection using for each. This is the preferred method.
   Console::WriteLine( "Displays the elements using for each:" );
   PrintKeysAndValues1( myCol );

   // Display the contents of the collection using the enumerator.
   Console::WriteLine( "Displays the elements using the IDictionaryEnumerator:" );
   PrintKeysAndValues2( myCol );

   // Display the contents of the collection using the Keys, Values, Count, and Item properties.
   Console::WriteLine( "Displays the elements using the Keys, Values, Count, and Item properties:" );
   PrintKeysAndValues3( myCol );
}

// Uses the foreach statement which hides the complexity of the enumerator.
// NOTE: The foreach statement is the preferred way of enumerating the contents of a collection.
void PrintKeysAndValues1( IDictionary^ myCol )  {
   Console::WriteLine( "   KEY                       VALUE" );
   for each ( DictionaryEntry^ de in myCol )
      Console::WriteLine( "   {0,-25} {1}", de->Key, de->Value );
   Console::WriteLine();
}

// Uses the enumerator. 
void PrintKeysAndValues2( IDictionary^ myCol )
{
   IDictionaryEnumerator^ myEnumerator = myCol->GetEnumerator();
   Console::WriteLine( "   KEY                       VALUE" );
   while ( myEnumerator->MoveNext() )
      Console::WriteLine( "   {0,-25} {1}", myEnumerator->Key, myEnumerator->Value );

   Console::WriteLine();
}

// Uses the Keys, Values, Count, and Item properties.
void PrintKeysAndValues3( HybridDictionary^ myCol )
{
   array<String^>^myKeys = gcnew array<String^>(myCol->Count);
   myCol->Keys->CopyTo( myKeys, 0 );
   Console::WriteLine( "   INDEX KEY                       VALUE" );
   for ( int i = 0; i < myCol->Count; i++ )
      Console::WriteLine( "   {0,-5} {1,-25} {2}", i, myKeys[ i ], myCol[ myKeys[ i ] ] );
   Console::WriteLine();
}

/*
This code produces output similar to the following:

Displays the elements using for each:
   KEY                       VALUE
   Seedless Watermelon       0.49
   Nectarine                 1.99
   Cranberries               5.98
   Plantain Bananas          1.49
   Honeydew Melon            0.59
   Pineapple                 1.49
   Strawberries              3.33
   Grapes                    1.99
   Braeburn Apples           1.49
   Peaches                   1.99
   Red Delicious Apples      0.99
   Golden Delicious Apples   1.29
   Yellow Bananas            0.79
   Granny Smith Apples       0.89
   Gala Apples               1.49
   Plums                     1.69
   Navel Oranges             1.29
   Fuji Apples               1.29

Displays the elements using the IDictionaryEnumerator:
   KEY                       VALUE
   Seedless Watermelon       0.49
   Nectarine                 1.99
   Cranberries               5.98
   Plantain Bananas          1.49
   Honeydew Melon            0.59
   Pineapple                 1.49
   Strawberries              3.33
   Grapes                    1.99
   Braeburn Apples           1.49
   Peaches                   1.99
   Red Delicious Apples      0.99
   Golden Delicious Apples   1.29
   Yellow Bananas            0.79
   Granny Smith Apples       0.89
   Gala Apples               1.49
   Plums                     1.69
   Navel Oranges             1.29
   Fuji Apples               1.29

Displays the elements using the Keys, Values, Count, and Item properties:
   INDEX KEY                       VALUE
   0     Seedless Watermelon       0.49
   1     Nectarine                 1.99
   2     Cranberries               5.98
   3     Plantain Bananas          1.49
   4     Honeydew Melon            0.59
   5     Pineapple                 1.49
   6     Strawberries              3.33
   7     Grapes                    1.99
   8     Braeburn Apples           1.49
   9     Peaches                   1.99
   10    Red Delicious Apples      0.99
   11    Golden Delicious Apples   1.29
   12    Yellow Bananas            0.79
   13    Granny Smith Apples       0.89
   14    Gala Apples               1.49
   15    Plums                     1.69
   16    Navel Oranges             1.29
   17    Fuji Apples               1.29

*/
using System;
using System.Collections;
using System.Collections.Specialized;

public class SamplesHybridDictionary  {

   public static void Main()  {

      // Creates and initializes a new HybridDictionary.
      HybridDictionary myCol = new HybridDictionary();
      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" );
      myCol.Add( "Plantain Bananas", "1.49" );
      myCol.Add( "Yellow Bananas", "0.79" );
      myCol.Add( "Strawberries", "3.33" );
      myCol.Add( "Cranberries", "5.98" );
      myCol.Add( "Navel Oranges", "1.29" );
      myCol.Add( "Grapes", "1.99" );
      myCol.Add( "Honeydew Melon", "0.59" );
      myCol.Add( "Seedless Watermelon", "0.49" );
      myCol.Add( "Pineapple", "1.49" );
      myCol.Add( "Nectarine", "1.99" );
      myCol.Add( "Plums", "1.69" );
      myCol.Add( "Peaches", "1.99" );

      // Display the contents of the collection using foreach. This is the preferred method.
      Console.WriteLine( "Displays the elements using foreach:" );
      PrintKeysAndValues1( myCol );

      // Display the contents of the collection using the enumerator.
      Console.WriteLine( "Displays the elements using the IDictionaryEnumerator:" );
      PrintKeysAndValues2( myCol );

      // Display the contents of the collection using the Keys, Values, Count, and Item properties.
      Console.WriteLine( "Displays the elements using the Keys, Values, Count, and Item properties:" );
      PrintKeysAndValues3( myCol );
   }

   // Uses the foreach statement which hides the complexity of the enumerator.
   // NOTE: The foreach statement is the preferred way of enumerating the contents of a collection.
   public static void PrintKeysAndValues1( IDictionary myCol )  {
      Console.WriteLine( "   KEY                       VALUE" );
      foreach ( DictionaryEntry de in myCol )
         Console.WriteLine( "   {0,-25} {1}", de.Key, de.Value );
      Console.WriteLine();
   }

   // Uses the enumerator.
   // NOTE: The foreach statement is the preferred way of enumerating the contents of a collection.
   public static void PrintKeysAndValues2( IDictionary myCol )  {
      IDictionaryEnumerator myEnumerator = myCol.GetEnumerator();
      Console.WriteLine( "   KEY                       VALUE" );
      while ( myEnumerator.MoveNext() )
         Console.WriteLine( "   {0,-25} {1}", myEnumerator.Key, myEnumerator.Value );
      Console.WriteLine();
   }

   // Uses the Keys, Values, Count, and Item properties.
   public static void PrintKeysAndValues3( HybridDictionary myCol )  {
      String[] myKeys = new String[myCol.Count];
      myCol.Keys.CopyTo( myKeys, 0 );

      Console.WriteLine( "   INDEX KEY                       VALUE" );
      for ( int i = 0; i < myCol.Count; i++ )
         Console.WriteLine( "   {0,-5} {1,-25} {2}", i, myKeys[i], myCol[myKeys[i]] );
      Console.WriteLine();
   }
}

/*
This code produces output similar to the following:

Displays the elements using foreach:
   KEY                       VALUE
   Seedless Watermelon       0.49
   Nectarine                 1.99
   Cranberries               5.98
   Plantain Bananas          1.49
   Honeydew Melon            0.59
   Pineapple                 1.49
   Strawberries              3.33
   Grapes                    1.99
   Braeburn Apples           1.49
   Peaches                   1.99
   Red Delicious Apples      0.99
   Golden Delicious Apples   1.29
   Yellow Bananas            0.79
   Granny Smith Apples       0.89
   Gala Apples               1.49
   Plums                     1.69
   Navel Oranges             1.29
   Fuji Apples               1.29

Displays the elements using the IDictionaryEnumerator:
   KEY                       VALUE
   Seedless Watermelon       0.49
   Nectarine                 1.99
   Cranberries               5.98
   Plantain Bananas          1.49
   Honeydew Melon            0.59
   Pineapple                 1.49
   Strawberries              3.33
   Grapes                    1.99
   Braeburn Apples           1.49
   Peaches                   1.99
   Red Delicious Apples      0.99
   Golden Delicious Apples   1.29
   Yellow Bananas            0.79
   Granny Smith Apples       0.89
   Gala Apples               1.49
   Plums                     1.69
   Navel Oranges             1.29
   Fuji Apples               1.29

Displays the elements using the Keys, Values, Count, and Item properties:
   INDEX KEY                       VALUE
   0     Seedless Watermelon       0.49
   1     Nectarine                 1.99
   2     Cranberries               5.98
   3     Plantain Bananas          1.49
   4     Honeydew Melon            0.59
   5     Pineapple                 1.49
   6     Strawberries              3.33
   7     Grapes                    1.99
   8     Braeburn Apples           1.49
   9     Peaches                   1.99
   10    Red Delicious Apples      0.99
   11    Golden Delicious Apples   1.29
   12    Yellow Bananas            0.79
   13    Granny Smith Apples       0.89
   14    Gala Apples               1.49
   15    Plums                     1.69
   16    Navel Oranges             1.29
   17    Fuji Apples               1.29

*/
Imports System.Collections
Imports System.Collections.Specialized

Public Class SamplesHybridDictionary   

   Public Shared Sub Main()

      ' Creates and initializes a new HybridDictionary.
      Dim myCol As New HybridDictionary()
      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")
      myCol.Add("Plantain Bananas", "1.49")
      myCol.Add("Yellow Bananas", "0.79")
      myCol.Add("Strawberries", "3.33")
      myCol.Add("Cranberries", "5.98")
      myCol.Add("Navel Oranges", "1.29")
      myCol.Add("Grapes", "1.99")
      myCol.Add("Honeydew Melon", "0.59")
      myCol.Add("Seedless Watermelon", "0.49")
      myCol.Add("Pineapple", "1.49")
      myCol.Add("Nectarine", "1.99")
      myCol.Add("Plums", "1.69")
      myCol.Add("Peaches", "1.99")

      ' Display the contents of the collection using For Each. This is the preferred method.
      Console.WriteLine("Displays the elements using For Each:")
      PrintKeysAndValues1(myCol)

      ' Display the contents of the collection using the enumerator.
      Console.WriteLine("Displays the elements using the IDictionaryEnumerator:")
      PrintKeysAndValues2(myCol)

      ' Display the contents of the collection using the Keys, Values, Count, and Item properties.
      Console.WriteLine("Displays the elements using the Keys, Values, Count, and Item properties:")
      PrintKeysAndValues3(myCol)

   End Sub


   ' Uses the For Each statement which hides the complexity of the enumerator.
   ' NOTE: The For Each statement is the preferred way of enumerating the contents of a collection.
   Public Shared Sub PrintKeysAndValues1(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


   ' Uses the enumerator. 
   ' NOTE: The For Each statement is the preferred way of enumerating the contents of a collection.
   Public Shared Sub PrintKeysAndValues2(myCol As IDictionary)
      Dim myEnumerator As IDictionaryEnumerator = myCol.GetEnumerator()

      Console.WriteLine("   KEY                       VALUE")
      While myEnumerator.MoveNext()
         Console.WriteLine("   {0,-25} {1}", myEnumerator.Key, myEnumerator.Value)
      End While
      Console.WriteLine()

   End Sub


   ' Uses the Keys, Values, Count, and Item properties.
   Public Shared Sub PrintKeysAndValues3(myCol As HybridDictionary)
      Dim myKeys(myCol.Count) As [String]
      myCol.Keys.CopyTo(myKeys, 0)

      Console.WriteLine("   INDEX KEY                       VALUE")
      Dim i As Integer
      For i = 0 To myCol.Count - 1
         Console.WriteLine("   {0,-5} {1,-25} {2}", i, myKeys(i), myCol(myKeys(i)))
      Next i
      Console.WriteLine()

   End Sub

End Class


'This code produces output similar to the following:
'
'Displays the elements using For Each:
'   KEY                       VALUE
'   Seedless Watermelon       0.49
'   Nectarine                 1.99
'   Cranberries               5.98
'   Plantain Bananas          1.49
'   Honeydew Melon            0.59
'   Pineapple                 1.49
'   Strawberries              3.33
'   Grapes                    1.99
'   Braeburn Apples           1.49
'   Peaches                   1.99
'   Red Delicious Apples      0.99
'   Golden Delicious Apples   1.29
'   Yellow Bananas            0.79
'   Granny Smith Apples       0.89
'   Gala Apples               1.49
'   Plums                     1.69
'   Navel Oranges             1.29
'   Fuji Apples               1.29
'
'Displays the elements using the IDictionaryEnumerator:
'   KEY                       VALUE
'   Seedless Watermelon       0.49
'   Nectarine                 1.99
'   Cranberries               5.98
'   Plantain Bananas          1.49
'   Honeydew Melon            0.59
'   Pineapple                 1.49
'   Strawberries              3.33
'   Grapes                    1.99
'   Braeburn Apples           1.49
'   Peaches                   1.99
'   Red Delicious Apples      0.99
'   Golden Delicious Apples   1.29
'   Yellow Bananas            0.79
'   Granny Smith Apples       0.89
'   Gala Apples               1.49
'   Plums                     1.69
'   Navel Oranges             1.29
'   Fuji Apples               1.29
'
'Displays the elements using the Keys, Values, Count, and Item properties:
'   INDEX KEY                       VALUE
'   0     Seedless Watermelon       0.49
'   1     Nectarine                 1.99
'   2     Cranberries               5.98
'   3     Plantain Bananas          1.49
'   4     Honeydew Melon            0.59
'   5     Pineapple                 1.49
'   6     Strawberries              3.33
'   7     Grapes                    1.99
'   8     Braeburn Apples           1.49
'   9     Peaches                   1.99
'   10    Red Delicious Apples      0.99
'   11    Golden Delicious Apples   1.29
'   12    Yellow Bananas            0.79
'   13    Granny Smith Apples       0.89
'   14    Gala Apples               1.49
'   15    Plums                     1.69
'   16    Navel Oranges             1.29
'   17    Fuji Apples               1.29

Hinweise

Die foreach-Anweisung der Programmiersprache C# (for each in Visual Basic) verbirgt die Komplexität der Enumeratoren. Daher empfiehlt es sich, foreach zu verwenden und den Enumerator nicht direkt zu ändern.

Mit Enumeratoren können die Daten in der Auflistung zwar gelesen, jedoch nicht zum Ändern der zugrunde liegenden Auflistung verwendet werden.

Zu Beginn wird der Enumerator vor das erste Element in der Auflistung positioniert. Reset setzt den Enumerator ebenfalls auf diese Position zurück. An dieser Position ist Current nicht definiert. Daher muss der Enumerator durch einen Aufruf von MoveNext auf das erste Element der Auflistung gesetzt werden, bevor der Wert von Current gelesen werden kann.

Current gibt solange dasselbe Objekt zurück, bis MoveNext oder Reset aufgerufen wird. MoveNext legt Current auf das nächste Element fest.

Wenn MoveNext das Ende der Auflistung übergibt, wird der Enumerator hinter dem letzten Element in der Auflistung platziert, und MoveNext gibt false zurück. Wenn sich der Enumerator an dieser Position befindet, geben nachfolgende Aufrufe von MoveNext auch false zurück. Wenn der letzte Aufruf MoveNext zurückgegebene false, Current ist nicht definiert. Um Current wieder auf das erste Element der Auflistung festzulegen, können Sie Reset gefolgt von MoveNext aufrufen.

Ein Enumerator bleibt gültig, solange die Auflistung unverändert bleibt. Werden an der Auflistung Änderungen wie z. B. Hinzufügen, Bearbeiten oder Entfernen von Elementen vorgenommen, verliert der Enumerator unwiederbringlich seine Gültigkeit und sein Verhalten ist nicht definiert.

Der Enumerator hat keinen exklusiven Zugriff auf die Auflistung; daher ist die Enumeration einer Auflistung systembedingt kein threadsicheres Verfahren. Um während der Enumeration Threadsicherheit zu garantieren, können Sie die Auflistung während der gesamten Enumeration sperren. Um den Lese- und Schreibzugriff auf diese Auflistung durch mehrere Threads zuzulassen, müssen Sie eine eigene Synchronisierung implementieren.

Diese Methode ist ein O(1)-Vorgang.

Gilt für:

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