ReadOnlyCollection<T>.GetEnumerator ReadOnlyCollection<T>.GetEnumerator ReadOnlyCollection<T>.GetEnumerator ReadOnlyCollection<T>.GetEnumerator Method

정의

ReadOnlyCollection<T>를 반복하는 열거자를 반환합니다.Returns an enumerator that iterates through the ReadOnlyCollection<T>.

public:
 virtual System::Collections::Generic::IEnumerator<T> ^ GetEnumerator();
public System.Collections.Generic.IEnumerator<T> GetEnumerator ();
abstract member GetEnumerator : unit -> System.Collections.Generic.IEnumerator<'T>
override this.GetEnumerator : unit -> System.Collections.Generic.IEnumerator<'T>
Public Function GetEnumerator () As IEnumerator(Of T)

반환

구현

예제

다음 코드 예제는 열거자를 사용 하 여의 내용을 표시 하는 ReadOnlyCollection<T> 래핑하는 List<T>합니다.The following code example uses the enumerator to display the contents of a ReadOnlyCollection<T> that wraps a List<T>. 로 열거자가 숨겨집니다 합니다 foreach 문 (For Each Visual basic에서는 for each c + +에서).The enumerator is concealed by the foreach statement (For Each in Visual Basic, for each in C++).

using namespace System;
using namespace System::Collections::Generic;
using namespace System::Collections::ObjectModel;

void main()
{
    List<String^>^ dinosaurs = gcnew List<String^>();

    dinosaurs->Add("Tyrannosaurus");
    dinosaurs->Add("Amargasaurus");
    dinosaurs->Add("Deinonychus");
    dinosaurs->Add("Compsognathus");

    ReadOnlyCollection<String^>^ readOnlyDinosaurs = 
        gcnew ReadOnlyCollection<String^>(dinosaurs);

    Console::WriteLine();
    for each(String^ dinosaur in readOnlyDinosaurs )
    {
        Console::WriteLine(dinosaur);
    }

    Console::WriteLine("\nCount: {0}", readOnlyDinosaurs->Count);

    Console::WriteLine("\nContains(\"Deinonychus\"): {0}", 
        readOnlyDinosaurs->Contains("Deinonychus"));

    Console::WriteLine("\nreadOnlyDinosaurs[3]: {0}", 
        readOnlyDinosaurs[3]);

    Console::WriteLine("\nIndexOf(\"Compsognathus\"): {0}", 
        readOnlyDinosaurs->IndexOf("Compsognathus"));

    Console::WriteLine("\nInsert into the wrapped List:");
    Console::WriteLine("Insert(2, \"Oviraptor\")");
    dinosaurs->Insert(2, "Oviraptor");

    Console::WriteLine();
    for each( String^ dinosaur in readOnlyDinosaurs )
    {
        Console::WriteLine(dinosaur);
    }

    array<String^>^ dinoArray = 
        gcnew array<String^>(readOnlyDinosaurs->Count + 2);
    readOnlyDinosaurs->CopyTo(dinoArray, 1);

    Console::WriteLine("\nCopied array has {0} elements:", 
        dinoArray->Length);
    for each( String^ dinosaur in dinoArray )
    {
        Console::WriteLine("\"{0}\"", dinosaur);
    }
}

/* This code example produces the following output:

Tyrannosaurus
Amargasaurus
Deinonychus
Compsognathus

Count: 4

Contains("Deinonychus"): True

readOnlyDinosaurs[3]: Compsognathus

IndexOf("Compsognathus"): 3

Insert into the wrapped List:
Insert(2, "Oviraptor")

Tyrannosaurus
Amargasaurus
Oviraptor
Deinonychus
Compsognathus

Copied array has 7 elements:
""
"Tyrannosaurus"
"Amargasaurus"
"Oviraptor"
"Deinonychus"
"Compsognathus"
""
 */
using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;

public class Example
{
    public static void Main()
    {
        List<string> dinosaurs = new List<string>();

        dinosaurs.Add("Tyrannosaurus");
        dinosaurs.Add("Amargasaurus");
        dinosaurs.Add("Deinonychus");
        dinosaurs.Add("Compsognathus");

        ReadOnlyCollection<string> readOnlyDinosaurs = 
            new ReadOnlyCollection<string>(dinosaurs);

        Console.WriteLine();
        foreach( string dinosaur in readOnlyDinosaurs )
        {
            Console.WriteLine(dinosaur);
        }

        Console.WriteLine("\nCount: {0}", readOnlyDinosaurs.Count);

        Console.WriteLine("\nContains(\"Deinonychus\"): {0}", 
            readOnlyDinosaurs.Contains("Deinonychus"));

        Console.WriteLine("\nreadOnlyDinosaurs[3]: {0}", 
            readOnlyDinosaurs[3]);

        Console.WriteLine("\nIndexOf(\"Compsognathus\"): {0}", 
            readOnlyDinosaurs.IndexOf("Compsognathus"));

        Console.WriteLine("\nInsert into the wrapped List:");
        Console.WriteLine("Insert(2, \"Oviraptor\")");
        dinosaurs.Insert(2, "Oviraptor");

        Console.WriteLine();
        foreach( string dinosaur in readOnlyDinosaurs )
        {
            Console.WriteLine(dinosaur);
        }

        string[] dinoArray = new string[readOnlyDinosaurs.Count + 2];
        readOnlyDinosaurs.CopyTo(dinoArray, 1);

        Console.WriteLine("\nCopied array has {0} elements:", 
            dinoArray.Length);
        foreach( string dinosaur in dinoArray )
        {
            Console.WriteLine("\"{0}\"", dinosaur);
        }
    }
}

/* This code example produces the following output:

Tyrannosaurus
Amargasaurus
Deinonychus
Compsognathus

Count: 4

Contains("Deinonychus"): True

readOnlyDinosaurs[3]: Compsognathus

IndexOf("Compsognathus"): 3

Insert into the wrapped List:
Insert(2, "Oviraptor")

Tyrannosaurus
Amargasaurus
Oviraptor
Deinonychus
Compsognathus

Copied array has 7 elements:
""
"Tyrannosaurus"
"Amargasaurus"
"Oviraptor"
"Deinonychus"
"Compsognathus"
""
 */
Imports System.Collections.Generic
Imports System.Collections.ObjectModel

Public Class Example

    Public Shared Sub Main()

        Dim dinosaurs As New List(Of String)

        dinosaurs.Add("Tyrannosaurus")
        dinosaurs.Add("Amargasaurus")
        dinosaurs.Add("Deinonychus")
        dinosaurs.Add("Compsognathus")

        Dim readOnlyDinosaurs As _
            New ReadOnlyCollection(Of String)(dinosaurs)

        Console.WriteLine()
        For Each dinosaur As String In readOnlyDinosaurs
            Console.WriteLine(dinosaur)
        Next

        Console.WriteLine(vbLf & "Count: {0}", _
            readOnlyDinosaurs.Count)

        Console.WriteLine(vbLf & "Contains(""Deinonychus""): {0}", _
            readOnlyDinosaurs.Contains("Deinonychus"))

        Console.WriteLine(vbLf & _
            "readOnlyDinosaurs(3): {0}", readOnlyDinosaurs(3))

        Console.WriteLine(vbLf & "IndexOf(""Compsognathus""): {0}", _
            readOnlyDinosaurs.IndexOf("Compsognathus"))

        Console.WriteLine(vbLf & "Insert into the wrapped List:")
        Console.WriteLine("Insert(2, ""Oviraptor"")")
        dinosaurs.Insert(2, "Oviraptor")

        Console.WriteLine()
        For Each dinosaur As String In readOnlyDinosaurs
            Console.WriteLine(dinosaur)
        Next

        Dim dinoArray(readOnlyDinosaurs.Count + 1) As String
        readOnlyDinosaurs.CopyTo(dinoArray, 1)

        Console.WriteLine(vbLf & "Copied array has {0} elements:", _
            dinoArray.Length)
        For Each dinosaur As String In dinoArray
            Console.WriteLine("""{0}""", dinosaur)
        Next

   End Sub
End Class

' This code example produces the following output:
'
'Tyrannosaurus
'Amargasaurus
'Deinonychus
'Compsognathus
'
'Count: 4
'
'Contains("Deinonychus"): True
'
'readOnlyDinosaurs(3): Compsognathus
'
'IndexOf("Compsognathus"): 3
'
'Insert into the wrapped List:
'Insert(2, "Oviraptor")
'
'Tyrannosaurus
'Amargasaurus
'Oviraptor
'Deinonychus
'Compsognathus
'
'Copied array has 7 elements:
'""
'"Tyrannosaurus"
'"Amargasaurus"
'"Oviraptor"
'"Deinonychus"
'"Compsognathus"
'""

설명

합니다 foreach C# 언어의 (for each Visual c + +에서는 For Each Visual basic에서) 열거자의 복잡성을 숨깁니다.The foreach statement of the C# language (for each in Visual C++, For Each in Visual Basic) hides the complexity of the enumerators. 그러므로 열거자를 직접 조작하는 대신 foreach를 사용하는 것이 좋습니다.Therefore, using foreach is recommended, instead of directly manipulating the enumerator.

열거자를 사용하여 컬렉션의 데이터를 읽을 수는 있지만 내부 컬렉션을 수정할 수는 없습니다.Enumerators can be used to read the data in the collection, but they cannot be used to modify the underlying collection.

처음에 열거자는 컬렉션의 첫 번째 요소 앞에 배치됩니다.Initially, the enumerator is positioned before the first element in the collection. 이 위치에서 Current는 정의되지 않습니다.At this position, Current is undefined. 따라서 MoveNext의 값을 읽기 전에 Current를 호출하여 열거자를 해당 컬렉션의 첫 번째 요소로 보내야 합니다.Therefore, you must call MoveNext to advance the enumerator to the first element of the collection before reading the value of Current.

CurrentMoveNext가 호출될 때까지 동일한 개체를 반환합니다.Current returns the same object until MoveNext is called. MoveNextCurrent를 다음 요소로 설정합니다.MoveNext sets Current to the next element.

경우 MoveNext 열거자를 컬렉션의 끝 컬렉션의 마지막 요소 뒤에 배치 되는 전달 하 고 MoveNext 반환 false합니다.If MoveNext passes the end of the collection, the enumerator is positioned after the last element in the collection and MoveNext returns false. 열거자가 있는 경우이 위치에 대 한 후속 호출은 MoveNext 반환할 수도 false합니다.When the enumerator is at this position, subsequent calls to MoveNext also return false. 마지막으로 호출 하는 경우 MoveNext 반환 false, Current 정의 되지 않습니다.If the last call to MoveNext returned false, Current is undefined. Current를 컬렉션의 첫 번째 요소로 다시 설정할 수 없으므로 대신 새 열거자 인스턴스를 만들어야 합니다.You cannot set Current to the first element of the collection again; you must create a new enumerator instance instead.

열거자는 컬렉션이 변경되지 않은 상태로 유지되는 한 유효한 상태를 유지합니다.An enumerator remains valid as long as the collection remains unchanged. 컬렉션에 대해 변경 내용을 수행하면(예: 요소 추가, 수정 또는 삭제) 열거자는 복구 불가능하게 무효화되고 해당 동작은 정의되지 않습니다.If changes are made to the collection, such as adding, modifying, or deleting elements, the enumerator is irrecoverably invalidated and its behavior is undefined.

열거자는 컬렉션에 배타적으로 액세스하지 못하므로 컬렉션을 열거하는 것은 본질적으로 스레드로부터 안전한 프로시저가 아닙니다.The enumerator does not have exclusive access to the collection; therefore, enumerating through a collection is intrinsically not a thread-safe procedure. 열거 동안 스레드 보안을 보장하려면 전체 열거 동안 컬렉션을 잠그면 됩니다.To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. 여러 스레드에서 컬렉션에 액세스하여 읽고 쓸 수 있도록 허용하려면 사용자 지정 동기화를 구현해야 합니다.To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.

컬렉션의 기본 구현은 System.Collections.Generic 동기화 되지 않습니다.Default implementations of collections in System.Collections.Generic are not synchronized.

이 방법은 O(1) 작업에 설명 합니다.This method is an O(1) operation.

적용 대상

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