다음을 통해 공유


CollectionBase.GetEnumerator 메서드

정의

CollectionBase 인스턴스를 반복하는 열거자를 반환합니다.

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

반환

CollectionBase 인스턴스에 대한 IEnumerator입니다.

구현

예제

다음 코드 예제에서는 구현 합니다 CollectionBase 클래스를 사용 하 여 해당 구현을 개체의 Int16 컬렉션을 만듭니다.

#using <System.dll>

using namespace System;
using namespace System::Collections;

public ref class Int16Collection: public CollectionBase
{
public:

   property Int16 Item [int]
   {
      Int16 get( int index )
      {
         return ( (Int16)(List[ index ]));
      }

      void set( int index, Int16 value )
      {
         List[ index ] = value;
      }
   }
   int Add( Int16 value )
   {
      return (List->Add( value ));
   }

   int IndexOf( Int16 value )
   {
      return (List->IndexOf( value ));
   }

   void Insert( int index, Int16 value )
   {
      List->Insert( index, value );
   }

   void Remove( Int16 value )
   {
      List->Remove( value );
   }

   bool Contains( Int16 value )
   {
      // If value is not of type Int16, this will return false.
      return (List->Contains( value ));
   }

protected:
   virtual void OnInsert( int /*index*/, Object^ /*value*/ ) override
   {
      // Insert additional code to be run only when inserting values.
   }

   virtual void OnRemove( int /*index*/, Object^ /*value*/ ) override
   {
      // Insert additional code to be run only when removing values.
   }

   virtual void OnSet( int /*index*/, Object^ /*oldValue*/, Object^ /*newValue*/ ) override
   {
      // Insert additional code to be run only when setting values.
   }

   virtual void OnValidate( Object^ value ) override
   {
      if ( value->GetType() != Type::GetType( "System.Int16" ) )
            throw gcnew ArgumentException( "value must be of type Int16.","value" );
   }

};

void PrintIndexAndValues( Int16Collection^ myCol );
void PrintValues2( Int16Collection^ myCol );
int main()
{
   // Create and initialize a new CollectionBase.
   Int16Collection^ myI16 = gcnew Int16Collection;
   
   // Add elements to the collection.
   myI16->Add( (Int16)1 );
   myI16->Add( (Int16)2 );
   myI16->Add( (Int16)3 );
   myI16->Add( (Int16)5 );
   myI16->Add( (Int16)7 );

   // Display the contents of the collection using the enumerator.
   Console::WriteLine( "Contents of the collection (using enumerator):" );
   PrintValues2( myI16 );

   // Display the contents of the collection using the Count property and the Item property.
   Console::WriteLine( "Initial contents of the collection (using Count and Item):" );
   PrintIndexAndValues( myI16 );

   // Search the collection with Contains and IndexOf.
   Console::WriteLine( "Contains 3: {0}", myI16->Contains( 3 ) );
   Console::WriteLine( "2 is at index {0}.", myI16->IndexOf( 2 ) );
   Console::WriteLine();

   // Insert an element into the collection at index 3.
   myI16->Insert( 3, (Int16)13 );
   Console::WriteLine( "Contents of the collection after inserting at index 3:" );
   PrintIndexAndValues( myI16 );

   // Get and set an element using the index.
   myI16->Item[ 4 ] = 123;
   Console::WriteLine( "Contents of the collection after setting the element at index 4 to 123:" );
   PrintIndexAndValues( myI16 );

   // Remove an element from the collection.
   myI16->Remove( (Int16)2 );

   // Display the contents of the collection using the Count property and the Item property.
   Console::WriteLine( "Contents of the collection after removing the element 2:" );
   PrintIndexAndValues( myI16 );
}

// Uses the Count property and the Item property.
void PrintIndexAndValues( Int16Collection^ myCol )
{
   for ( int i = 0; i < myCol->Count; i++ )
      Console::WriteLine( "   [{0}]:   {1}", i, myCol->Item[ i ] );
   Console::WriteLine();
}

// Uses the enumerator. 
void PrintValues2( Int16Collection^ myCol )
{
   System::Collections::IEnumerator^ myEnumerator = myCol->GetEnumerator();
   while ( myEnumerator->MoveNext() )
      Console::WriteLine( "   {0}", myEnumerator->Current );

   Console::WriteLine();
}

/* 
This code produces the following output.

Contents of the collection (using enumerator):
   1
   2
   3
   5
   7

Initial contents of the collection (using Count and Item):
   [0]:   1
   [1]:   2
   [2]:   3
   [3]:   5
   [4]:   7

Contains 3: True
2 is at index 1.

Contents of the collection after inserting at index 3:
   [0]:   1
   [1]:   2
   [2]:   3
   [3]:   13
   [4]:   5
   [5]:   7

Contents of the collection after setting the element at index 4 to 123:
   [0]:   1
   [1]:   2
   [2]:   3
   [3]:   13
   [4]:   123
   [5]:   7

Contents of the collection after removing the element 2:
   [0]:   1
   [1]:   3
   [2]:   13
   [3]:   123
   [4]:   7

*/
using System;
using System.Collections;

public class Int16Collection : CollectionBase  {

   public Int16 this[ int index ]  {
      get  {
         return( (Int16) List[index] );
      }
      set  {
         List[index] = value;
      }
   }

   public int Add( Int16 value )  {
      return( List.Add( value ) );
   }

   public int IndexOf( Int16 value )  {
      return( List.IndexOf( value ) );
   }

   public void Insert( int index, Int16 value )  {
      List.Insert( index, value );
   }

   public void Remove( Int16 value )  {
      List.Remove( value );
   }

   public bool Contains( Int16 value )  {
      // If value is not of type Int16, this will return false.
      return( List.Contains( value ) );
   }

   protected override void OnInsert( int index, Object value )  {
      // Insert additional code to be run only when inserting values.
   }

   protected override void OnRemove( int index, Object value )  {
      // Insert additional code to be run only when removing values.
   }

   protected override void OnSet( int index, Object oldValue, Object newValue )  {
      // Insert additional code to be run only when setting values.
   }

   protected override void OnValidate( Object value )  {
      if ( value.GetType() != typeof(System.Int16) )
         throw new ArgumentException( "value must be of type Int16.", "value" );
   }
}

public class SamplesCollectionBase  {

   public static void Main()  {

      // Create and initialize a new CollectionBase.
      Int16Collection myI16 = new Int16Collection();

      // Add elements to the collection.
      myI16.Add( (Int16) 1 );
      myI16.Add( (Int16) 2 );
      myI16.Add( (Int16) 3 );
      myI16.Add( (Int16) 5 );
      myI16.Add( (Int16) 7 );

      // Display the contents of the collection using foreach. This is the preferred method.
      Console.WriteLine( "Contents of the collection (using foreach):" );
      PrintValues1( myI16 );

      // Display the contents of the collection using the enumerator.
      Console.WriteLine( "Contents of the collection (using enumerator):" );
      PrintValues2( myI16 );

      // Display the contents of the collection using the Count property and the Item property.
      Console.WriteLine( "Initial contents of the collection (using Count and Item):" );
      PrintIndexAndValues( myI16 );

      // Search the collection with Contains and IndexOf.
      Console.WriteLine( "Contains 3: {0}", myI16.Contains( 3 ) );
      Console.WriteLine( "2 is at index {0}.", myI16.IndexOf( 2 ) );
      Console.WriteLine();

      // Insert an element into the collection at index 3.
      myI16.Insert( 3, (Int16) 13 );
      Console.WriteLine( "Contents of the collection after inserting at index 3:" );
      PrintIndexAndValues( myI16 );

      // Get and set an element using the index.
      myI16[4] = 123;
      Console.WriteLine( "Contents of the collection after setting the element at index 4 to 123:" );
      PrintIndexAndValues( myI16 );

      // Remove an element from the collection.
      myI16.Remove( (Int16) 2 );

      // Display the contents of the collection using the Count property and the Item property.
      Console.WriteLine( "Contents of the collection after removing the element 2:" );
      PrintIndexAndValues( myI16 );
   }

   // Uses the Count property and the Item property.
   public static void PrintIndexAndValues( Int16Collection myCol )  {
      for ( int i = 0; i < myCol.Count; i++ )
         Console.WriteLine( "   [{0}]:   {1}", i, myCol[i] );
      Console.WriteLine();
   }

   // 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 PrintValues1( Int16Collection myCol )  {
      foreach ( Int16 i16 in myCol )
         Console.WriteLine( "   {0}", i16 );
      Console.WriteLine();
   }

   // Uses the enumerator.
   // NOTE: The foreach statement is the preferred way of enumerating the contents of a collection.
   public static void PrintValues2( Int16Collection myCol )  {
      System.Collections.IEnumerator myEnumerator = myCol.GetEnumerator();
      while ( myEnumerator.MoveNext() )
         Console.WriteLine( "   {0}", myEnumerator.Current );
      Console.WriteLine();
   }
}


/*
This code produces the following output.

Contents of the collection (using foreach):
   1
   2
   3
   5
   7

Contents of the collection (using enumerator):
   1
   2
   3
   5
   7

Initial contents of the collection (using Count and Item):
   [0]:   1
   [1]:   2
   [2]:   3
   [3]:   5
   [4]:   7

Contains 3: True
2 is at index 1.

Contents of the collection after inserting at index 3:
   [0]:   1
   [1]:   2
   [2]:   3
   [3]:   13
   [4]:   5
   [5]:   7

Contents of the collection after setting the element at index 4 to 123:
   [0]:   1
   [1]:   2
   [2]:   3
   [3]:   13
   [4]:   123
   [5]:   7

Contents of the collection after removing the element 2:
   [0]:   1
   [1]:   3
   [2]:   13
   [3]:   123
   [4]:   7

*/
Imports System.Collections


Public Class Int16Collection
   Inherits CollectionBase


   Default Public Property Item(index As Integer) As Int16
      Get
         Return CType(List(index), Int16)
      End Get
      Set
         List(index) = value
      End Set
   End Property


   Public Function Add(value As Int16) As Integer
      Return List.Add(value)
   End Function 'Add

   Public Function IndexOf(value As Int16) As Integer
      Return List.IndexOf(value)
   End Function 'IndexOf


   Public Sub Insert(index As Integer, value As Int16)
      List.Insert(index, value)
   End Sub


   Public Sub Remove(value As Int16)
      List.Remove(value)
   End Sub


   Public Function Contains(value As Int16) As Boolean
      ' If value is not of type Int16, this will return false.
      Return List.Contains(value)
   End Function 'Contains


   Protected Overrides Sub OnInsert(index As Integer, value As Object)
      ' Insert additional code to be run only when inserting values.
   End Sub


   Protected Overrides Sub OnRemove(index As Integer, value As Object)
      ' Insert additional code to be run only when removing values.
   End Sub


   Protected Overrides Sub OnSet(index As Integer, oldValue As Object, newValue As Object)
      ' Insert additional code to be run only when setting values.
   End Sub


   Protected Overrides Sub OnValidate(value As Object)
      If Not GetType(System.Int16).IsAssignableFrom(value.GetType()) Then
         Throw New ArgumentException("value must be of type Int16.", "value")
      End If
   End Sub

End Class


Public Class SamplesCollectionBase

   Public Shared Sub Main()

      ' Creates and initializes a new CollectionBase.
      Dim myI16 As New Int16Collection()

      ' Adds elements to the collection.
      myI16.Add( 1 )
      myI16.Add( 2 )
      myI16.Add( 3 )
      myI16.Add( 5 )
      myI16.Add( 7 )

      ' Display the contents of the collection using For Each. This is the preferred method.
      Console.WriteLine("Contents of the collection (using For Each):")
      PrintValues1(myI16)
      
      ' Display the contents of the collection using the enumerator.
      Console.WriteLine("Contents of the collection (using enumerator):")
      PrintValues2(myI16)
      
      ' Display the contents of the collection using the Count property and the Item property.
      Console.WriteLine("Initial contents of the collection (using Count and Item):")
      PrintIndexAndValues(myI16)
      
      ' Searches the collection with Contains and IndexOf.
      Console.WriteLine("Contains 3: {0}", myI16.Contains(3))
      Console.WriteLine("2 is at index {0}.", myI16.IndexOf(2))
      Console.WriteLine()
      
      ' Inserts an element into the collection at index 3.
      myI16.Insert(3, 13)
      Console.WriteLine("Contents of the collection after inserting at index 3:")
      PrintIndexAndValues(myI16)
      
      ' Gets and sets an element using the index.
      myI16(4) = 123
      Console.WriteLine("Contents of the collection after setting the element at index 4 to 123:")
      PrintIndexAndValues(myI16)
      
      ' Removes an element from the collection.
      myI16.Remove(2)

      ' Display the contents of the collection using the Count property and the Item property.
      Console.WriteLine("Contents of the collection after removing the element 2:")
      PrintIndexAndValues(myI16)

    End Sub


    ' Uses the Count property and the Item property.
    Public Shared Sub PrintIndexAndValues(myCol As Int16Collection)
      Dim i As Integer
      For i = 0 To myCol.Count - 1
          Console.WriteLine("   [{0}]:   {1}", i, myCol(i))
      Next i
      Console.WriteLine()
    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 PrintValues1(myCol As Int16Collection)
      Dim i16 As Int16
      For Each i16 In  myCol
          Console.WriteLine("   {0}", i16)
      Next i16
      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 PrintValues2(myCol As Int16Collection)
      Dim myEnumerator As System.Collections.IEnumerator = myCol.GetEnumerator()
      While myEnumerator.MoveNext()
          Console.WriteLine("   {0}", myEnumerator.Current)
      End While
      Console.WriteLine()
    End Sub

End Class


'This code produces the following output.
'
'Contents of the collection (using For Each):
'   1
'   2
'   3
'   5
'   7
'
'Contents of the collection (using enumerator):
'   1
'   2
'   3
'   5
'   7
'
'Initial contents of the collection (using Count and Item):
'   [0]:   1
'   [1]:   2
'   [2]:   3
'   [3]:   5
'   [4]:   7
'
'Contains 3: True
'2 is at index 1.
'
'Contents of the collection after inserting at index 3:
'   [0]:   1
'   [1]:   2
'   [2]:   3
'   [3]:   13
'   [4]:   5
'   [5]:   7
'
'Contents of the collection after setting the element at index 4 to 123:
'   [0]:   1
'   [1]:   2
'   [2]:   3
'   [3]:   13
'   [4]:   123
'   [5]:   7
'
'Contents of the collection after removing the element 2:
'   [0]:   1
'   [1]:   3
'   [2]:   13
'   [3]:   123
'   [4]:   7

설명

@FSHO1@C# 언어의 foreach 문(Visual Basic의 경우 for each)은 열거자의 복잡성을 숨깁니다. 그러므로 열거자를 직접 조작하는 대신 foreach를 사용하는 것이 좋습니다.

열거자를 사용하여 컬렉션의 데이터를 읽을 수는 있지만 내부 컬렉션을 수정할 수는 없습니다.

처음에 열거자는 컬렉션의 첫 번째 요소 앞에 배치됩니다. Reset을 실행하면 열거자가 이 위치로 복원됩니다. 이 위치에서, 호출 Current 예외를 throw 합니다. 따라서 MoveNext의 값을 읽기 전에 Current를 호출하여 열거자를 해당 컬렉션의 첫 번째 요소로 보내야 합니다.

Current에서는 MoveNext 또는 Reset이 호출될 때까지 동일한 개체를 반환합니다. MoveNextCurrent를 다음 요소로 설정합니다.

경우 MoveNext 열거자를 컬렉션의 끝 컬렉션의 마지막 요소 뒤에 배치 되는 전달 하 고 MoveNext 반환 false합니다. 열거자가 있는 경우이 위치에 대 한 후속 호출은 MoveNext 반환할 수도 false합니다. 마지막으로 호출 하는 경우 MoveNext 반환 false호출, Current 예외를 throw 합니다. Current를 컬렉션의 첫째 요소에 다시 설정하려면 Reset을 호출한 뒤 MoveNext를 호출해야 합니다.

컬렉션이 변경되지 않고 그대로 유지되는 한 열거자는 유효한 상태로 유지됩니다. 변경에 추가 하는 등 컬렉션을 수정 하거나 요소를 삭제, 열거자가 복구할 유효 하지 않으며을 다음에 호출할 MoveNext 또는 Reset throw는 InvalidOperationException합니다. 컬렉션 사이 수정 된 경우 MoveNext 하 고 Current, Current 열거자가 이미 무효화 된 경우에로 설정 되어 있는 요소를 반환 합니다.

열거자는 컬렉션에 독점적으로 액세스할 수 있는 권한이 없으므로 컬렉션을 열거하는 프로시저는 기본적으로 스레드로부터 안전하지 않습니다. 컬렉션이 동기화되어 있을 때 다른 스레드에서 해당 컬렉션을 수정할 수 있으므로 이렇게 되면 열거자에서 예외가 throw됩니다. 열거하는 동안 스레드로부터 안전을 보장하려면 전체 열거를 수행하는 동안 컬렉션을 잠그거나 다른 스레드에서 변경된 내용으로 인해 발생한 예외를 catch하면 됩니다.

메서드는 GetEnumerator 기본적으로 COM 클라이언트에 표시되지 않지만 클래스를 상속하면 메서드가 CollectionBase 노출될 수 있으며 COM 클라이언트에서 바람직하지 않은 동작이 발생할 수 있습니다.

이 메서드는 작업입니다 O(1) .

적용 대상

추가 정보