ArrayList.ReadOnly メソッド

定義

読み取り専用のリスト ラッパーを返します。

オーバーロード

ReadOnly(ArrayList)

読み取り専用 ArrayList ラッパーを返します。

ReadOnly(IList)

読み取り専用 IList ラッパーを返します。

ReadOnly(ArrayList)

読み取り専用 ArrayList ラッパーを返します。

public:
 static System::Collections::ArrayList ^ ReadOnly(System::Collections::ArrayList ^ list);
public static System.Collections.ArrayList ReadOnly (System.Collections.ArrayList list);
static member ReadOnly : System.Collections.ArrayList -> System.Collections.ArrayList
Public Shared Function ReadOnly (list As ArrayList) As ArrayList

パラメーター

list
ArrayList

ラップする ArrayList

戻り値

ArrayList

list をラップする読み取り専用の ArrayList ラッパー。

例外

listnullです。

次のコード例は、読み取り専用ラッパーを作成する方法と、読み取り ArrayList 専用かどうかを判断する方法を ArrayList 示しています。

#using <system.dll>

using namespace System;
using namespace System::Collections;
int main()
{
   
   // Creates and initializes a new ArrayList.
   ArrayList^ myAL = gcnew ArrayList;
   myAL->Add( "red" );
   myAL->Add( "orange" );
   myAL->Add( "yellow" );
   
   // Creates a read-only copy of the ArrayList.
   ArrayList^ myReadOnlyAL = ArrayList::ReadOnly( myAL );
   
   // Displays whether the ArrayList is read-only or writable.
   Console::WriteLine( "myAL is {0}.", myAL->IsReadOnly ? (String^)"read-only" : "writable" );
   Console::WriteLine( "myReadOnlyAL is {0}.", myReadOnlyAL->IsReadOnly ? (String^)"read-only" : "writable" );
   
   // Displays the contents of both collections.
   Console::WriteLine( "\nInitially," );
   Console::WriteLine( "The original ArrayList myAL contains:" );
   for ( int i(0); i < myAL->Count; ++i )
      Console::WriteLine(  "   {0}", static_cast<String^>(myAL[ i ]) );
   Console::WriteLine( "The read-only ArrayList myReadOnlyAL contains:" );
   for ( int i(0); i < myReadOnlyAL->Count; ++i )
      Console::WriteLine( "   {0}", static_cast<String^>(myReadOnlyAL[ i ]) );
   
   // Adding an element to a read-only ArrayList throws an exception.
   Console::WriteLine( "\nTrying to add a new element to the read-only ArrayList:" );
   try
   {
      myReadOnlyAL->Add( "green" );
   }
   catch ( Exception^ myException ) 
   {
      Console::WriteLine( String::Concat( "Exception: ", myException->ToString() ) );
   }

   
   // Adding an element to the original ArrayList affects the read-only ArrayList.
   myAL->Add( "blue" );
   
   // Displays the contents of both collections again.
   Console::WriteLine( "\nAfter adding a new element to the original ArrayList," );
   Console::WriteLine( "The original ArrayList myAL contains:" );
   for ( int i(0); i < myAL->Count; ++i )
      Console::WriteLine( "   {0}", static_cast<String^>(myAL[ i ]) );
   Console::WriteLine( "The read-only ArrayList myReadOnlyAL contains:" );
   for ( int i(0); i < myReadOnlyAL->Count; ++i )
      Console::WriteLine( "   {0}", static_cast<String^>(myReadOnlyAL[ i ]) );
}

/*
This code produces the following output.

myAL is writable.
myReadOnlyAL is read-only.

Initially,
The original ArrayList myAL contains:
   red
   orange
   yellow
The read-only ArrayList myReadOnlyAL contains:
   red
   orange
   yellow

Trying to add a new element to the read-only ArrayList:
Exception: System.NotSupportedException: Collection is read-only.
   at System.Collections.ReadOnlyArrayList.Add(Object obj)
   at SamplesArrayList.Main()

After adding a new element to the original ArrayList,
The original ArrayList myAL contains:
   red
   orange
   yellow
   blue
The read-only ArrayList myReadOnlyAL contains:
   red
   orange
   yellow
   blue

*/
 using System;
 using System.Collections;
 public class SamplesArrayList  {

    public static void Main()  {

       // Creates and initializes a new ArrayList.
       ArrayList myAL = new ArrayList();
       myAL.Add( "red" );
       myAL.Add( "orange" );
       myAL.Add( "yellow" );

       // Creates a read-only copy of the ArrayList.
       ArrayList myReadOnlyAL = ArrayList.ReadOnly( myAL );

       // Displays whether the ArrayList is read-only or writable.
       Console.WriteLine( "myAL is {0}.", myAL.IsReadOnly ? "read-only" : "writable" );
       Console.WriteLine( "myReadOnlyAL is {0}.", myReadOnlyAL.IsReadOnly ? "read-only" : "writable" );

       // Displays the contents of both collections.
       Console.WriteLine( "\nInitially," );
       Console.WriteLine( "The original ArrayList myAL contains:" );
       foreach ( string myStr in myAL )
          Console.WriteLine( "   {0}", myStr );
       Console.WriteLine( "The read-only ArrayList myReadOnlyAL contains:" );
       foreach ( string myStr in myReadOnlyAL )
          Console.WriteLine( "   {0}", myStr );

       // Adding an element to a read-only ArrayList throws an exception.
       Console.WriteLine( "\nTrying to add a new element to the read-only ArrayList:" );
       try  {
          myReadOnlyAL.Add("green");
       } catch ( Exception myException )  {
          Console.WriteLine("Exception: " + myException.ToString());
       }

       // Adding an element to the original ArrayList affects the read-only ArrayList.
       myAL.Add( "blue" );

       // Displays the contents of both collections again.
       Console.WriteLine( "\nAfter adding a new element to the original ArrayList," );
       Console.WriteLine( "The original ArrayList myAL contains:" );
       foreach ( string myStr in myAL )
          Console.WriteLine( "   {0}", myStr );
       Console.WriteLine( "The read-only ArrayList myReadOnlyAL contains:" );
       foreach ( string myStr in myReadOnlyAL )
          Console.WriteLine( "   {0}", myStr );
    }
 }


/*
This code produces the following output.

myAL is writable.
myReadOnlyAL is read-only.

Initially,
The original ArrayList myAL contains:
   red
   orange
   yellow
The read-only ArrayList myReadOnlyAL contains:
   red
   orange
   yellow

Trying to add a new element to the read-only ArrayList:
Exception: System.NotSupportedException: Collection is read-only.
   at System.Collections.ReadOnlyArrayList.Add(Object obj)
   at SamplesArrayList.Main()

After adding a new element to the original ArrayList,
The original ArrayList myAL contains:
   red
   orange
   yellow
   blue
The read-only ArrayList myReadOnlyAL contains:
   red
   orange
   yellow
   blue

*/
Imports System.Collections

Public Class SamplesArrayList

   Public Shared Sub Main()

      Dim myStr As [String]

      ' Creates and initializes a new ArrayList.
      Dim myAL As New ArrayList()
      myAL.Add("red")
      myAL.Add("orange")
      myAL.Add("yellow")

      ' Creates a read-only copy of the ArrayList.
      Dim myReadOnlyAL As ArrayList = ArrayList.ReadOnly(myAL)

      ' Displays whether the ArrayList is read-only or writable.
      If myAL.IsReadOnly Then
         Console.WriteLine("myAL is read-only.")
      Else
         Console.WriteLine("myAL is writable.")
      End If
      If myReadOnlyAL.IsReadOnly Then
         Console.WriteLine("myReadOnlyAL is read-only.")
      Else
         Console.WriteLine("myReadOnlyAL is writable.")
      End If

      ' Displays the contents of both collections.
      Console.WriteLine()
      Console.WriteLine("Initially,")
      Console.WriteLine("The original ArrayList myAL contains:")
      For Each myStr In  myAL
         Console.WriteLine("   {0}", myStr)
      Next myStr
      Console.WriteLine("The read-only ArrayList myReadOnlyAL contains:")
      For Each myStr In  myReadOnlyAL
         Console.WriteLine("   {0}", myStr)
      Next myStr 

      ' Adding an element to a read-only ArrayList throws an exception.
      Console.WriteLine()
      Console.WriteLine("Trying to add a new element to the read-only ArrayList:")
      Try
         myReadOnlyAL.Add("green")
      Catch myException As Exception
         Console.WriteLine(("Exception: " + myException.ToString()))
      End Try

      ' Adding an element to the original ArrayList affects the read-only ArrayList.
      myAL.Add("blue")

      ' Displays the contents of both collections again.
      Console.WriteLine()
      Console.WriteLine("After adding a new element to the original ArrayList,")
      Console.WriteLine("The original ArrayList myAL contains:")
      For Each myStr In  myAL
         Console.WriteLine("   {0}", myStr)
      Next myStr
      Console.WriteLine("The read-only ArrayList myReadOnlyAL contains:")
      For Each myStr In  myReadOnlyAL
         Console.WriteLine("   {0}", myStr)
      Next myStr 

   End Sub

End Class


'This code produces the following output.
'
'myAL is writable.
'myReadOnlyAL is read-only.
'
'Initially,
'The original ArrayList myAL contains:
'   red
'   orange
'   yellow
'The read-only ArrayList myReadOnlyAL contains:
'   red
'   orange
'   yellow
'
'Trying to add a new element to the read-only ArrayList:
'Exception: System.NotSupportedException: Collection is read-only.
'   at System.Collections.ReadOnlyArrayList.Add(Object obj)
'   at SamplesArrayList.Main()
'
'After adding a new element to the original ArrayList,
'The original ArrayList myAL contains:
'   red
'   orange
'   yellow
'   blue
'The read-only ArrayList myReadOnlyAL contains:
'   red
'   orange
'   yellow
'   blue

注釈

への変更を list防ぐには、このラッパーを介してのみ公開 list します。

読み取り専用のコレクションは、コレクションの変更を妨げるラッパーを持つ単なるコレクションです。 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それらの変更が反映されます。

このメソッドは操作です O(1)

こちらもご覧ください

適用対象

ReadOnly(IList)

読み取り専用 IList ラッパーを返します。

public:
 static System::Collections::IList ^ ReadOnly(System::Collections::IList ^ list);
public static System.Collections.IList ReadOnly (System.Collections.IList list);
static member ReadOnly : System.Collections.IList -> System.Collections.IList
Public Shared Function ReadOnly (list As IList) As IList

パラメーター

list
IList

ラップする IList

戻り値

IList

list をラップする読み取り専用の IList ラッパー。

例外

listnullです。

注釈

への変更を list防ぐには、このラッパーを介してのみ公開 list します。

読み取り専用のコレクションは、コレクションの変更を妨げるラッパーを持つ単なるコレクションです。 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それらの変更が反映されます。

このメソッドは操作です O(1)

こちらもご覧ください

適用対象