ConcurrentDictionary<TKey,TValue>.TryAdd(TKey, TValue) Metoda

Definicja

Przestrzeń nazw:

System.Collections.Concurrent

Zestaw:

System.Collections.Concurrent.dll

Źródło:

ConcurrentDictionary.cs

Próbuje dodać określony klucz i wartość do elementu ConcurrentDictionary<TKey,TValue>.

public:
 bool TryAdd(TKey key, TValue value);

public bool TryAdd (TKey key, TValue value);

member this.TryAdd : 'Key * 'Value -> bool

Public Function TryAdd (key As TKey, value As TValue) As Boolean

Parametry

key

TKey

Klucz elementu do dodania.

value

TValue

Wartość elementu do dodania. Wartość może być null przeznaczona dla typów referencyjnych.

Zwraca

Boolean

true jeśli para klucz/wartość została dodana pomyślnie ConcurrentDictionary<TKey,TValue> ; false jeśli klucz już istnieje.

Wyjątki

ArgumentNullException

key to null.

OverflowException

Słownik zawiera zbyt wiele elementów.

Przykłady

W poniższym przykładzie pokazano, jak wywołać metodę ConcurrentDictionary<TKey,TValue>.TryAdd :

class CD_TryXYZ
{
        // Demonstrates:
        //      ConcurrentDictionary<TKey, TValue>.TryAdd()
        //      ConcurrentDictionary<TKey, TValue>.TryUpdate()
        //      ConcurrentDictionary<TKey, TValue>.TryRemove()
        static void Main()
        {
            int numFailures = 0; // for bookkeeping

            // Construct an empty dictionary
            ConcurrentDictionary<int, String> cd = new ConcurrentDictionary<int, string>();

            // This should work
            if (!cd.TryAdd(1, "one"))
            {
                Console.WriteLine("CD.TryAdd() failed when it should have succeeded");
                numFailures++;
            }

            // This shouldn't work -- key 1 is already in use
            if (cd.TryAdd(1, "uno"))
            {
                Console.WriteLine("CD.TryAdd() succeeded when it should have failed");
                numFailures++;
            }

            // Now change the value for key 1 from "one" to "uno" -- should work
            if (!cd.TryUpdate(1, "uno", "one"))
            {
                Console.WriteLine("CD.TryUpdate() failed when it should have succeeded");
                numFailures++;
            }

            // Try to change the value for key 1 from "eine" to "one"
            //    -- this shouldn't work, because the current value isn't "eine"
            if (cd.TryUpdate(1, "one", "eine"))
            {
                Console.WriteLine("CD.TryUpdate() succeeded when it should have failed");
                numFailures++;
            }

            // Remove key/value for key 1.  Should work.
            string value1;
            if (!cd.TryRemove(1, out value1))
            {
                Console.WriteLine("CD.TryRemove() failed when it should have succeeded");
                numFailures++;
            }

            // Remove key/value for key 1.  Shouldn't work, because I already removed it
            string value2;
            if (cd.TryRemove(1, out value2))
            {
                Console.WriteLine("CD.TryRemove() succeeded when it should have failed");
                numFailures++;
            }

            // If nothing went wrong, say so
            if (numFailures == 0) Console.WriteLine("  OK!");
        }
}

// Demonstrates:
//      ConcurrentDictionary<TKey, TValue>.TryAdd()
//      ConcurrentDictionary<TKey, TValue>.TryUpdate()
//      ConcurrentDictionary<TKey, TValue>.TryRemove()

let mutable numFailures = 0 // for bookkeeping

// Construct an empty dictionary
let cd = ConcurrentDictionary<int, string>()

// This should work
if cd.TryAdd(1, "one") |> not then
    printfn "CD.TryAdd() failed when it should have succeeded"
    numFailures <- numFailures + 1

// This shouldn't work -- key 1 is already in use
if cd.TryAdd(1, "uno") then
    printfn "CD.TryAdd() succeeded when it should have failed"
    numFailures <- numFailures + 1

// Now change the value for key 1 from "one" to "uno" -- should work
if cd.TryUpdate(1, "uno", "one") |> not then
    printfn "CD.TryUpdate() failed when it should have succeeded"
    numFailures <- numFailures + 1

// Try to change the value for key 1 from "eine" to "one"
//    -- this shouldn't work, because the current value isn't "eine"
if cd.TryUpdate(1, "one", "eine") then
    printfn "CD.TryUpdate() succeeded when it should have failed"
    numFailures <- numFailures + 1

// Remove key/value for key 1.  Should work.
let mutable value1 = ""

if cd.TryRemove(1, &value1) |> not then
    printfn "CD.TryRemove() failed when it should have succeeded"
    numFailures <- numFailures + 1

// Remove key/value for key 1.  Shouldn't work, because I already removed it
let mutable value2 = ""

if cd.TryRemove(1, &value2) then
    printfn "CD.TryRemove() succeeded when it should have failed"
    numFailures <- numFailures + 1

// If nothing went wrong, say so
if numFailures = 0 then
    printfn "  OK!"

'Imports System.Collections.Concurrent

Class CD_TryXYZ

    ' Demonstrates:
    ' ConcurrentDictionary<TKey, TValue>.TryAdd()
    ' ConcurrentDictionary<TKey, TValue>.TryUpdate()
    ' ConcurrentDictionary<TKey, TValue>.TryRemove()
    Shared Sub Main()
        Dim numFailures As Integer = 0
        ' for bookkeeping
        ' Construct an empty dictionary
        Dim cd As ConcurrentDictionary(Of Integer, [String]) = New ConcurrentDictionary(Of Integer, String)()

        ' This should work
        If Not cd.TryAdd(1, "one") Then
            Console.WriteLine("CD.TryAdd() failed when it should have succeeded")
            numFailures += 1
        End If

        ' This shouldn't work -- key 1 is already in use
        If cd.TryAdd(1, "uno") Then
            Console.WriteLine("CD.TryAdd() succeeded when it should have failed")
            numFailures += 1
        End If

        ' Now change the value for key 1 from "one" to "uno" -- should work
        If Not cd.TryUpdate(1, "uno", "one") Then
            Console.WriteLine("CD.TryUpdate() failed when it should have succeeded")
            numFailures += 1
        End If

        ' Try to change the value for key 1 from "eine" to "one" 
        ' -- this shouldn't work, because the current value isn't "eine"
        If cd.TryUpdate(1, "one", "eine") Then
            Console.WriteLine("CD.TryUpdate() succeeded when it should have failed")
            numFailures += 1
        End If

        ' Remove key/value for key 1. Should work.
        Dim value1 As String = ""
        If Not cd.TryRemove(1, value1) Then
            Console.WriteLine("CD.TryRemove() failed when it should have succeeded")
            numFailures += 1
        End If

        ' Remove key/value for key 1. Shouldn't work, because I already removed it
        Dim value2 As String = ""
        If cd.TryRemove(1, value2) Then
            Console.WriteLine("CD.TryRemove() succeeded when it should have failed")
            numFailures += 1
        End If

        ' If nothing went wrong, say so
        If numFailures = 0 Then
            Console.WriteLine(" OK!")
        End If
    End Sub
End Class

Uwagi

Ta metoda zwraca wartość false , jeśli klucz już istnieje. TryUpdate Użyj metody orAddOrUpdate, aby zaktualizować wartość w przypadku, gdy klucz już istnieje.

Zobacz też

• Kolekcje bezpieczne wątkowo
• Instrukcje: Dodawanie elementów do kolekcji ConcurrentDictionary i ich usuwanie