ReadOnlyCollectionBase Class
Provides the abstract base class for a strongly typed non-generic read-only collection.
Assembly: mscorlib (in mscorlib.dll)
System.Collections::ReadOnlyCollectionBase
System.ComponentModel::ComponentCollection
System.Configuration::ConfigurationLocationCollection
System.Diagnostics::ProcessModuleCollection
System.Diagnostics::ProcessThreadCollection
System.DirectoryServices.ActiveDirectory::ActiveDirectoryRoleCollection
System.DirectoryServices.ActiveDirectory::AdamInstanceCollection
System.DirectoryServices.ActiveDirectory::AdamRoleCollection
System.DirectoryServices.ActiveDirectory::ApplicationPartitionCollection
System.DirectoryServices.ActiveDirectory::AttributeMetadataCollection
System.DirectoryServices.ActiveDirectory::DomainCollection
System.DirectoryServices.ActiveDirectory::DomainControllerCollection
System.DirectoryServices.ActiveDirectory::ForestTrustDomainInfoCollection
System.DirectoryServices.ActiveDirectory::ForestTrustRelationshipCollisionCollection
System.DirectoryServices.ActiveDirectory::GlobalCatalogCollection
System.DirectoryServices.ActiveDirectory::ReadOnlyActiveDirectorySchemaClassCollection
System.DirectoryServices.ActiveDirectory::ReadOnlyActiveDirectorySchemaPropertyCollection
System.DirectoryServices.ActiveDirectory::ReadOnlyDirectoryServerCollection
System.DirectoryServices.ActiveDirectory::ReadOnlySiteCollection
System.DirectoryServices.ActiveDirectory::ReadOnlySiteLinkBridgeCollection
System.DirectoryServices.ActiveDirectory::ReadOnlySiteLinkCollection
System.DirectoryServices.ActiveDirectory::ReadOnlyStringCollection
System.DirectoryServices.ActiveDirectory::ReplicationConnectionCollection
System.DirectoryServices.ActiveDirectory::ReplicationCursorCollection
System.DirectoryServices.ActiveDirectory::ReplicationFailureCollection
System.DirectoryServices.ActiveDirectory::ReplicationNeighborCollection
System.DirectoryServices.ActiveDirectory::ReplicationOperationCollection
System.DirectoryServices.ActiveDirectory::TopLevelNameCollection
System.DirectoryServices.ActiveDirectory::TrustRelationshipInformationCollection
System.DirectoryServices.Protocols::PartialResultsCollection
System.DirectoryServices.Protocols::SearchResultEntryCollection
System.DirectoryServices.Protocols::SearchResultReferenceCollection
System.DirectoryServices::ResultPropertyValueCollection
System.Drawing.Design::CategoryNameCollection
System.Drawing.Design::ToolboxItemCollection
System.Security.AccessControl::AuthorizationRuleCollection
System.Security.Authentication.ExtendedProtection::ServiceNameCollection
System.Web.Management::WebBaseEventCollection
System.Web.UI.Design::ClientScriptItemCollection
System.Web.UI.WebControls.WebParts::CatalogPartCollection
System.Web.UI.WebControls.WebParts::ConnectionInterfaceCollection
System.Web.UI.WebControls.WebParts::ConsumerConnectionPointCollection
System.Web.UI.WebControls.WebParts::EditorPartCollection
System.Web.UI.WebControls.WebParts::ProviderConnectionPointCollection
System.Web.UI.WebControls.WebParts::TransformerTypeCollection
System.Web.UI.WebControls.WebParts::WebPartCollection
System.Web.UI.WebControls.WebParts::WebPartDescriptionCollection
System.Web.UI.WebControls.WebParts::WebPartVerbCollection
System.Web.UI.WebControls.WebParts::WebPartZoneCollection
System.Windows.Forms::FormCollection
System.Windows.Forms::InputLanguageCollection
| Name | Description | |
|---|---|---|
![]() | ReadOnlyCollectionBase() | Initializes a new instance of the ReadOnlyCollectionBase class. |
| Name | Description | |
|---|---|---|
![]() | Equals(Object^) | Determines whether the specified object is equal to the current object.(Inherited from Object.) |
![]() | Finalize() | Allows an object to try to free resources and perform other cleanup operations before it is reclaimed by garbage collection.(Inherited from Object.) |
![]() | GetEnumerator() | Returns an enumerator that iterates through the ReadOnlyCollectionBase instance. |
![]() | GetHashCode() | Serves as the default hash function. (Inherited from Object.) |
![]() | GetType() | |
![]() | MemberwiseClone() | |
![]() | ToString() | Returns a string that represents the current object.(Inherited from Object.) |
| Name | Description | |
|---|---|---|
![]() ![]() | ICollection::CopyTo(Array^, Int32) | Copies the entire ReadOnlyCollectionBase to a compatible one-dimensional Array, starting at the specified index of the target array. |
![]() ![]() | ICollection::IsSynchronized | Gets a value indicating whether access to a ReadOnlyCollectionBase object is synchronized (thread safe). |
![]() ![]() | ICollection::SyncRoot | Gets an object that can be used to synchronize access to a ReadOnlyCollectionBase object. |
| Name | Description | |
|---|---|---|
![]() | AsParallel() | Overloaded. Enables parallelization of a query.(Defined by ParallelEnumerable.) |
![]() | AsQueryable() | Overloaded. Converts an IEnumerable to an IQueryable.(Defined by Queryable.) |
![]() | Cast<TResult>() | Casts the elements of an IEnumerable to the specified type.(Defined by Enumerable.) |
![]() | OfType<TResult>() | Filters the elements of an IEnumerable based on a specified type.(Defined by Enumerable.) |
A ReadOnlyCollectionBase instance is always read-only. See CollectionBase for a modifiable version of this class.
Notes to Implementers:
This base class is provided to make it easier for implementers to create a strongly typed read-only custom collection. Implementers are encouraged to extend this base class instead of creating their own. Members of this base class are protected and are intended to be used through a derived class only.
This class makes the underlying collection available through the InnerList property, which is intended for use only by classes that are derived directly from ReadOnlyCollectionBase. The derived class must ensure that its own users cannot modify the underlying collection.
The following code example implements the ReadOnlyCollectionBase class.
using namespace System; using namespace System::Collections; public ref class ROCollection: public ReadOnlyCollectionBase { public: ROCollection( IList^ sourceList ) { InnerList->AddRange( sourceList ); } property Object^ Item [int] { Object^ get( int index ) { return (InnerList[ index ]); } } int IndexOf( Object^ value ) { return (InnerList->IndexOf( value )); } bool Contains( Object^ value ) { return (InnerList->Contains( value )); } }; void PrintIndexAndValues( ROCollection^ myCol ); void PrintValues2( ROCollection^ myCol ); int main() { // Create an ArrayList. ArrayList^ myAL = gcnew ArrayList; myAL->Add( "red" ); myAL->Add( "blue" ); myAL->Add( "yellow" ); myAL->Add( "green" ); myAL->Add( "orange" ); myAL->Add( "purple" ); // Create a new ROCollection that contains the elements in myAL. ROCollection^ myCol = gcnew ROCollection( myAL ); // Display the contents of the collection using the enumerator. Console::WriteLine( "Contents of the collection (using enumerator):" ); PrintValues2( myCol ); // Display the contents of the collection using the Count property and the Item property. Console::WriteLine( "Contents of the collection (using Count and Item):" ); PrintIndexAndValues( myCol ); // Search the collection with Contains and IndexOf. Console::WriteLine( "Contains yellow: {0}", myCol->Contains( "yellow" ) ); Console::WriteLine( "orange is at index {0}.", myCol->IndexOf( "orange" ) ); Console::WriteLine(); } // Uses the Count property and the Item property. void PrintIndexAndValues( ROCollection^ myCol ) { for ( int i = 0; i < myCol->Count; i++ ) Console::WriteLine( " [{0}]: {1}", i, myCol->Item[ i ] ); Console::WriteLine(); } // Uses the enumerator. void PrintValues2( ROCollection^ 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): red blue yellow green orange purple Contents of the collection (using Count and Item): [0]: red [1]: blue [2]: yellow [3]: green [4]: orange [5]: purple Contains yellow: True orange is at index 4. */
Available since 10
.NET Framework
Available since 1.1
Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
This implementation does not provide a synchronized (thread safe) wrapper for a ReadOnlyCollectionBase, but derived classes can create their own synchronized versions of the ReadOnlyCollectionBase using the SyncRoot property.
Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.






