ComponentCollection Class


Provides a read-only container for a collection of IComponent objects.

Namespace:   System.ComponentModel
Assembly:  System (in System.dll)


[HostProtectionAttribute(SecurityAction::LinkDemand, Synchronization = true)]
public ref class ComponentCollection : ReadOnlyCollectionBase


Initializes a new instance of the ComponentCollection class using the specified array of components.


Gets the number of elements contained in the ReadOnlyCollectionBase instance.(Inherited from ReadOnlyCollectionBase.)


Gets the list of elements contained in the ReadOnlyCollectionBase instance.(Inherited from ReadOnlyCollectionBase.)


Gets the Component in the collection at the specified collection index.


Gets any component in the collection matching the specified name.

System_CAPS_pubmethodCopyTo(array<IComponent^>^, Int32)

Copies the entire collection to an array, starting writing at the specified array index.


Determines whether the specified object is equal to the current object.(Inherited from Object.)


Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.)


Returns an enumerator that iterates through the ReadOnlyCollectionBase instance.(Inherited from ReadOnlyCollectionBase.)


Serves as the default hash function. (Inherited from Object.)


Gets the Type of the current instance.(Inherited from Object.)


Creates a shallow copy of the current Object.(Inherited from Object.)


Returns a string that represents the current object.(Inherited from Object.)

System_CAPS_pubinterfaceSystem_CAPS_privmethodICollection::CopyTo(Array^, Int32)

Copies the entire ReadOnlyCollectionBase to a compatible one-dimensional Array, starting at the specified index of the target array.(Inherited from ReadOnlyCollectionBase.)


Gets a value indicating whether access to a ReadOnlyCollectionBase object is synchronized (thread safe).(Inherited from ReadOnlyCollectionBase.)


Gets an object that can be used to synchronize access to a ReadOnlyCollectionBase object.(Inherited from ReadOnlyCollectionBase.)


Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.)


Overloaded. Converts an IEnumerable to an IQueryable.(Defined by Queryable.)


Casts the elements of an IEnumerable to the specified type.(Defined by Enumerable.)


Filters the elements of an IEnumerable based on a specified type.(Defined by Enumerable.)

This collection inherits from ReadOnlyCollectionBase. The only way to add IComponent objects to this collection is to use the class constructor.

This collection provides two indexer properties, a string indexer and an integer indexer. The string indexer property returns a component in the collection by name if the Site property of a component in the collection is not null and the Name property of the Site property of the component matches the specified string. The integer indexer property returns the IComponent at the specified collection index. The CopyTo method copies the contents of the collection to a specified array, beginning writing to the array at the specified index.

The following code example demonstrates how to use a ComponentCollection to enumerate a collection of custom BookComponent objects.

 //This code segment implements the IContainer interface.  The code segment
 //containing the implementation of ISite and IComponent can be found in the documentation
 //for those interfaces.
 //Implement the LibraryContainer using the IContainer interface.
 ref class LibraryContainer: public IContainer
    ArrayList^ m_bookList;

       m_bookList = gcnew ArrayList;

    virtual void Add( IComponent^ book )

       //The book will be added without creation of the ISite object.
       m_bookList->Add( book );

    virtual void Add( IComponent^ book, String^ ISNDNNum )
       for ( int i = 0; i < m_bookList->Count; ++i )
          IComponent^ curObj = static_cast<IComponent^>(m_bookList->default[ i ]);
          if ( curObj->Site != nullptr )
             if ( curObj->Site->Name->Equals( ISNDNNum ) )
                            throw gcnew SystemException( "The ISBN number already exists in the container" );

       ISBNSite^ data = gcnew ISBNSite( this,book );
       data->Name = ISNDNNum;
       book->Site = data;
       m_bookList->Add( book );

    virtual void Remove( IComponent^ book )
       for ( int i = 0; i < m_bookList->Count; ++i )
          if ( book->Equals( m_bookList->default[ i ] ) )
             m_bookList->RemoveAt( i );


    property ComponentCollection^ Components 
       virtual ComponentCollection^ get() 
          array<IComponent^>^datalist = gcnew array<BookComponent^>(m_bookList->Count);
          m_bookList->CopyTo( datalist );
          return gcnew ComponentCollection( datalist );


       for ( int i = 0; i < m_bookList->Count; ++i )
          IComponent^ curObj = static_cast<IComponent^>(m_bookList->default[ i ]);
          delete curObj;



 int main()
       LibraryContainer^ cntrExmpl = gcnew LibraryContainer;
          BookComponent^ book1 = gcnew BookComponent( "Wizard's First Rule","Terry Gooodkind" );
          cntrExmpl->Add( book1, "0812548051" );
          BookComponent^ book2 = gcnew BookComponent( "Stone of Tears","Terry Gooodkind" );
          cntrExmpl->Add( book2, "0812548094" );
          BookComponent^ book3 = gcnew BookComponent( "Blood of the Fold","Terry Gooodkind" );
          cntrExmpl->Add( book3, "0812551478" );
          BookComponent^ book4 = gcnew BookComponent( "The Soul of the Fire","Terry Gooodkind" );

          //This will generate exception because the ISBN already exists in the container.
          cntrExmpl->Add( book4, "0812551478" );
       catch ( SystemException^ e ) 
          Console::WriteLine(  "Error description: {0}", e->Message );

       ComponentCollection^ datalist = cntrExmpl->Components;
       IEnumerator^ denum = datalist->GetEnumerator();
       while ( denum->MoveNext() )
          BookComponent^ cmp = static_cast<BookComponent^>(denum->Current);
          Console::WriteLine( "Book Title: {0}", cmp->Title );
          Console::WriteLine(  "Book Author: {0}", cmp->Author );
          Console::WriteLine(  "Book ISBN: {0}", cmp->Site->Name );

return 0;

.NET Framework
Available since 1.1
Available since 2.0
Windows Phone Silverlight
Available since 7.0

Any public static ( Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.

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