RAD Studio VCL Reference
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TCollection Class

TCollection is a container for TCollectionItem objects.

Pascal
TCollection = class(TPersistent);
C++
class TCollection : public TPersistent;

Classes

Each TCollection holds a group of TCollectionItem descendants. TCollection maintains an index of the collection items in its Items array. The Count property contains the number of items in the collection. Use the Add and Delete methods to add items to the collection and delete items from the collection. 

Objects descended from TCollection can contain objects descended from TCollectionItem. Thus, for each TCollection descendant, there is a corresponding TCollectionItem descendant. The following table lists some typical descendants of TCollection with the corresponding TCollectionItem descendant and the component that uses each pair.

TCollection descendant 
TCollectionItem descendant 
Component 
TAggregates  
TAggregate  
TClientDataSet  
TCookieCollection  
TCookie  
TWebResponse  
TCoolBands  
TCoolBand  
TCoolBar  
TDBGridColumns  
TColumn  
TDBGrid  
TDependencies  
TDependency  
TService  
TDisplayDims  
TDisplayDim  
TDecisionGrid  
TFieldDefs  
TFieldDef  
TDataSet  
THeaderSections  
THeaderSection  
THeaderControl  
TIndexDefs  
TIndexDef  
TTable  
TListColumns  
TListColumn  
TListView  
TParams  
TParam  
many datasets  
TStatusPanels  
TStatusPanel  
TStatusBar  
TWorkAreas  
TWorkArea  
TListView  

The controls that use TCollection and TCollectionItem descendants have a published property that holds a collection. (For example, the Panels property of TStatusBar holds a TStatusPanels.) A standard property editor, referred to generically as the Collection editor, can be invoked from the Object Inspector to edit the items in the collection.

Note: When writing a TCollection descendant that is used by another control, be sure to override the protected GetOwner method of the collection so that it can appear in the Object Inspector.
 

TCollectionItem 

Working with Lists

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