HybridDictionary.GetEnumerator Método

Definição

Retorna um IDictionaryEnumerator que itera pelo HybridDictionary.Returns an IDictionaryEnumerator that iterates through the HybridDictionary.

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

Retornos

IDictionaryEnumerator

Um IDictionaryEnumerator para o HybridDictionary.An IDictionaryEnumerator for the HybridDictionary.

Implementações

Exemplos

O exemplo de código a seguir enumera os elementos de um HybridDictionary .The following code example enumerates the elements of a HybridDictionary.

#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

Comentários

A foreach instrução da linguagem C# ( for each em Visual Basic) oculta a complexidade dos enumeradores.The foreach statement of the C# language (for each in Visual Basic) hides the complexity of the enumerators. Portanto, o uso de foreach é recomendado, em vez de manipular diretamente o enumerador.Therefore, using foreach is recommended, instead of directly manipulating the enumerator.

Os enumeradores podem ser usados para ler os dados na coleção, mas não podem ser usados para modificar a coleção subjacente.Enumerators can be used to read the data in the collection, but they cannot be used to modify the underlying collection.

Inicialmente, o enumerador é posicionado antes do primeiro elemento da coleção.Initially, the enumerator is positioned before the first element in the collection. Reset também traz o enumerador de volta para essa posição.Reset also brings the enumerator back to this position. Nesta posição, Current está indefinido.At this position, Current is undefined. Por isso, você deve chamar MoveNext para avançar o enumerador até o primeiro elemento da coleção antes de ler o valor de Current.Therefore, you must call MoveNext to advance the enumerator to the first element of the collection before reading the value of Current.

Current retorna o mesmo objeto até MoveNext ou Reset ser chamado.Current returns the same object until either MoveNext or Reset is called. MoveNext define Current como o próximo elemento.MoveNext sets Current to the next element.

Caso MoveNext passe o final da coleção, o enumerador é posicionado após o último elemento na coleção e MoveNext retorna false.If MoveNext passes the end of the collection, the enumerator is positioned after the last element in the collection and MoveNext returns false. Quando o enumerador está nessa posição, as chamadas subsequentes para MoveNext também retornam false.When the enumerator is at this position, subsequent calls to MoveNext also return false. Caso a última chamada para MoveNext tenha retornado false, Current está indefinido.If the last call to MoveNext returned false, Current is undefined. Para definir Current como o primeiro elemento da coleção novamente, é possível chamar Reset seguido de MoveNext.To set Current to the first element of the collection again, you can call Reset followed by MoveNext.

Um enumerador permanece válido desde que a coleção permaneça inalterada.An enumerator remains valid as long as the collection remains unchanged. Se forem feitas alterações na coleção, como adicionar, modificar ou excluir elementos, o enumerador será invalidado de maneira irrevogável e seu comportamento permanecerá indefinido.If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and its behavior is undefined.

O enumerador não tem acesso exclusivo à coleção; por isso, a enumeração por meio de uma coleção não é um procedimento thread-safe intrínseco.The enumerator does not have exclusive access to the collection; therefore, enumerating through a collection is intrinsically not a thread-safe procedure. Para garantir acesso thread-safe durante a enumeração, é possível bloquear a coleção durante toda a enumeração.To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. Para permitir que a coleção seja acessada por vários threads para leitura e gravação, você deve implementar sua própria sincronização.To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.

Este método é uma operação O(1).This method is an O(1) operation.

Aplica-se a

Confira também