CollectionBase.OnSet(Int32, Object, Object) メソッド

定義

CollectionBase インスタンスに値を設定する前に、追加のカスタム プロセスを実行します。

protected:
 virtual void OnSet(int index, System::Object ^ oldValue, System::Object ^ newValue);
protected virtual void OnSet (int index, object oldValue, object newValue);
protected virtual void OnSet (int index, object? oldValue, object? newValue);
abstract member OnSet : int * obj * obj -> unit
override this.OnSet : int * obj * obj -> unit
Protected Overridable Sub OnSet (index As Integer, oldValue As Object, newValue As Object)

パラメーター

index
Int32

oldValue が存在する位置の、0 以上のインデックス番号。

oldValue
Object

newValue で置換する値。

newValue
Object

index にある要素の新しい値。

次のコード例では、 クラスを CollectionBase 実装し、その実装を使用して オブジェクトの Int16 コレクションを作成します。

#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

注釈

このメソッドの既定の実装は、指定した要素が設定される前に何らかのアクションを実行するために、派生クラスによってオーバーライドされることを意図しています。

On* メソッドは、 プロパティによって List 返されるインスタンスでのみ呼び出されますが、 プロパティによって InnerList 返されるインスタンスでは呼び出されません。

プロセスが失敗した場合、コレクションは以前の状態に戻ります。

このメソッドの既定の実装は 操作です O(1)

注意 (継承者)

このメソッドを使用すると、実装者は、基になる ArrayListで指定された要素を設定する前に実行する必要があるプロセスを定義できます。 このメソッドを定義することで、実装者は、他のすべてのメソッドをオーバーライドすることなく、継承されたメソッドに機能を追加できます。

OnSet(Int32, Object, Object) は標準の Set 動作の前に呼び出されますが OnSetComplete(Int32, Object, Object) 、標準の Set 動作の後に呼び出されます。

たとえば、実装者は、 内 OnSet(Int32, Object, Object)でチェックを実行することで、上書きできる値を制限できます。

OnValidate(Object) は、このメソッドの前に呼び出されます。

適用対象

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