AddOrUpdate Method (TKey, TValue, Func(TKey, TValue, TValue))

Task Parallel System.Threading

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Adds a key/value pair to the ConcurrentDictionary<(Of <(TKey, TValue>)>) if the key does not already exist, or updates a key/value pair in the ConcurrentDictionary<(Of <(TKey, TValue>)>) if the key already exists.

Namespace: System.Collections.Concurrent
Assembly: System.Threading (in System.Threading.dll)

Syntax

Visual Basic (Declaration)
Public Function AddOrUpdate ( _ key As TKey, _ addValue As TValue, _ updateValueFactory As Func(Of TKey, TValue, TValue) _ ) As TValue

C#
public TValue AddOrUpdate( TKey key, TValue addValue, Func<TKey, TValue, TValue> updateValueFactory )

Parameters

key: Type: TKey
The key to be added or whose value should be updated

addValue: Type: TValue
The value to be added for an absent key

updateValueFactory: Type: System..::.Func<(Of <(TKey, TValue, TValue>)>)
The function used to generate a new value for an existing key based on the key's existing value

Return Value

The new value for the key. This will be either be the result of addValueFactory (if the key was absent) or the result of updateValueFactory (if the key was present).

Exceptions

Exception	Condition
System..::.ArgumentNullException	key is a null reference (Nothing in Visual Basic).
System..::.ArgumentNullException	updateValueFactory is a null reference (Nothing in Visual Basic).
System..::.OverflowException	The dictionary contains too many elements.