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HybridDictionary.IEnumerable.GetEnumerator Metoda

Definice

Vrátí hodnotu IEnumerator , která iteruje přes HybridDictionary.

 virtual System::Collections::IEnumerator ^ System.Collections.IEnumerable.GetEnumerator() = System::Collections::IEnumerable::GetEnumerator;
System.Collections.IEnumerator IEnumerable.GetEnumerator ();
abstract member System.Collections.IEnumerable.GetEnumerator : unit -> System.Collections.IEnumerator
override this.System.Collections.IEnumerable.GetEnumerator : unit -> System.Collections.IEnumerator
Function GetEnumerator () As IEnumerator Implements IEnumerable.GetEnumerator

Návraty

An IEnumerator pro HybridDictionary.

Implementuje

Příklady

Následující příklad kódu vytvoří výčet prvků objektu 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

Poznámky

Příkaz foreach jazyka C# (for each v jazyce Visual Basic) skrývá složitost enumerátorů. Proto se doporučuje použít foreach místo přímé manipulace s enumerátorem.

Enumerátory lze používat ke čtení dat v kolekci, nikoli však k úpravě zdrojové kolekce.

Zpočátku je enumerátor umístěn před prvním prvkem v kolekci. Reset také vrátí enumerátor zpět na tuto pozici. Na této pozici vyvolá volání Current výjimku. Proto je nutné před čtením hodnoty Currentvolat MoveNext k posunu enumerátoru na první prvek kolekce.

Current vrátí stejný objekt, dokud není volána hodnota MoveNext nebo Reset . MoveNext nastaví Current na další prvek.

Pokud MoveNext projde konec kolekce, enumerátor se umístí za poslední prvek v kolekci a MoveNext vrátí false. Když je enumerátor na této pozici, následné volání také MoveNext vrátí false. Pokud se vrátilo falseposlední volání MoveNext , vyvolá volání Current výjimku. Pokud chcete znovu nastavit Current první prvek kolekce, můžete volat Reset a potom MoveNext.

Enumerátor zůstane platný, dokud kolekce zůstane beze změny. Pokud jsou v kolekci provedeny změny, například přidání, úprava nebo odstranění prvků, enumerátor je nenávratně zneplatněný a další volání MoveNext nebo Reset vyvolá InvalidOperationException. Pokud je kolekce změněna mezi MoveNext a Current, Current vrátí prvek, na který je nastavena, i když je enumerátor již zneplatněný.

Enumerátor nemá výhradní přístup ke kolekci; proto výčet prostřednictvím kolekce není vnitřně procedurou bezpečnou pro přístup z více vláken. I v případě, že jde o synchronizovanou kolekci, mohou úpravy provádět i ostatní vlákna, což způsobuje vyvolání výjimky enumerátorem. K zaručení bezpečnosti přístupu z více vláken můžete buďto zamknout kolekci na celou dobu práce s výčtem, nebo zachycovat výjimky vzniklé v důsledku změn prováděných ostatními vlákny.

Tato metoda je operace O(1).

Platí pro

Viz také