ReadOnlyCollection<T>(IList<T>) ReadOnlyCollection<T>(IList<T>) ReadOnlyCollection<T>(IList<T>) ReadOnlyCollection<T>(IList<T>) Constructor

定義

指定したリストをラップする読み取り専用のラッパーである、ReadOnlyCollection<T> クラスの新しいインスタンスを初期化します。Initializes a new instance of the ReadOnlyCollection<T> class that is a read-only wrapper around the specified list.

public:
 ReadOnlyCollection(System::Collections::Generic::IList<T> ^ list);
public ReadOnlyCollection (System.Collections.Generic.IList<T> list);
new System.Collections.ObjectModel.ReadOnlyCollection<'T> : System.Collections.Generic.IList<'T> -> System.Collections.ObjectModel.ReadOnlyCollection<'T>
Public Sub New (list As IList(Of T))

パラメーター

list
IList<T> IList<T> IList<T> IList<T>

ラップするリスト。The list to wrap.

例外

次のコード例は、このコンストラクターとReadOnlyCollection<T>クラスのいくつかのメンバーを示しています。The following code example demonstrates this constructor and several members of the ReadOnlyCollection<T> class.

このコード例ではList<T> 、文字列のを作成し、4つの恐竜名を追加します。The code example creates a List<T> of strings and adds four dinosaur names to it. このコード例では、コンストラクターに渡すReadOnlyCollection<T>ことによって、でリストをラップします。The code example then wraps the list in a ReadOnlyCollection<T> by passing it to the constructor.

、、 Item[Int32]CountおよびContains ReadOnlyCollection<T> List<T> List<T>の各メンバーをデモンストレーションした後、このコード例では、に新しい項目を追加することによって、が元ののラッパーであることを示しています。 IList.IndexOfの内容を表示ReadOnlyCollection<T>しています。After demonstrating the Count, Contains, Item[Int32], and IList.IndexOf members, the code example shows that the ReadOnlyCollection<T> is just a wrapper for the original List<T> by adding a new item to the List<T> and displaying the contents of the ReadOnlyCollection<T>.

最後に、コレクションよりも大きい配列を作成し、 CopyToメソッドを使用して、コレクションの要素を配列の途中に挿入します。Finally, the code example creates an array larger than the collection and uses the CopyTo method to insert the elements of the collection into the middle of the array.

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"
'""

注釈

list変更を加えないようにlistするには、このラッパーを通じてのみを公開します。To prevent any modifications to list, expose list only through this wrapper.

読み取り専用のコレクションは、単純にコレクションを変更できないようにするラッパーを含むコレクションです。したがって、基になるコレクションに変更が加えられた場合、読み取り専用コレクションにはこれらの変更が反映されます。A collection that is read-only is simply a collection with a wrapper that prevents modifying the collection; therefore, if changes are made to the underlying collection, the read-only collection reflects those changes.

このコンストラクターは O (1) 操作です。This constructor is an O(1) operation.

適用対象

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