[Overview][Constants][Types][Classes][Procedures and functions][Variables] | Reference for unit 'Classes' (#fcl)

# TCollection.Update

Hander called when an item in the collection has changed.

## Declaration

`protected procedure TCollection.Update(`
`Item: TCollectionItem`
`); virtual;`

## Description

Update is called in the following cases:

1. An item is added to or removed from the collection.
2. An item is moved in the list, i.e. its TCollectionItem.Index property changes.
3. An item's TCollectionItem.DisplayName property changes.

Descendent classes can override this method to perform additional actions when the collection changes. The Item parameter indicates the item that was changed. This can be Nil

## See also

TCollection.Changed |  | Procedure called if an item is added to or removed from the collection.