ConcurrentDictionary<TKey,TValue>.TryRemove Metodo

Definizione

Spazio dei nomi:

System.Collections.Concurrent

Assembly:

System.Collections.Concurrent.dll

Overload

TryRemove(TKey, TValue)	Tenta di rimuovere e restituire il valore con la chiave specificata da ConcurrentDictionary<TKey,TValue>.
TryRemove(KeyValuePair<TKey,TValue>)	Rimuove una chiave e un valore dal dizionario.

TryRemove(TKey, TValue)

Source:

ConcurrentDictionary.cs

Tenta di rimuovere e restituire il valore con la chiave specificata da ConcurrentDictionary<TKey,TValue>.

public:
 bool TryRemove(TKey key, [Runtime::InteropServices::Out] TValue % value);

public bool TryRemove (TKey key, out TValue value);

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

Public Function TryRemove (key As TKey, ByRef value As TValue) As Boolean

Parametri

key

TKey

Chiave dell'elemento da rimuovere e restituire.

value

TValue

Quando termina, questo metodo contiene l'oggetto rimosso da ConcurrentDictionary<TKey,TValue>o il valore predefinito del TValue tipo se key non esiste.

Restituisce

Boolean

true se l'oggetto è stato rimosso correttamente; in caso contrario, false.

Eccezioni

ArgumentNullException

key è null.

Esempio

Nell'esempio seguente viene illustrato come chiamare il ConcurrentDictionary<TKey,TValue>.TryRemove metodo :

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

Vedi anche

• Raccolte thread-safe
• Procedura: Aggiungere e rimuovere elementi da un oggetto ConcurrentDictionary

TryRemove(KeyValuePair<TKey,TValue>)

Source:

ConcurrentDictionary.cs

Rimuove una chiave e un valore dal dizionario.

public:
 bool TryRemove(System::Collections::Generic::KeyValuePair<TKey, TValue> item);

public bool TryRemove (System.Collections.Generic.KeyValuePair<TKey,TValue> item);

member this.TryRemove : System.Collections.Generic.KeyValuePair<'Key, 'Value> -> bool

Public Function TryRemove (item As KeyValuePair(Of TKey, TValue)) As Boolean

Parametri

item

KeyValuePair<TKey,TValue>

KeyValuePair<TKey,TValue> che rappresenta la chiave e il valore da rimuovere.

Restituisce

Boolean

true se la chiave e il valore rappresentati da item vengono trovati e rimossi; in caso contrario, false.

Eccezioni

ArgumentNullException

La proprietà Key di item è null.

Commenti

Sia la chiave specificata che il valore devono corrispondere alla voce nel dizionario affinché venga rimossa.

La chiave viene confrontata usando l'operatore di confronto del dizionario (o l'operatore di confronto predefinito per TKey se non è stato fornito alcun operatore di confronto al dizionario al momento della costruzione). Il valore viene confrontato usando l'operatore di confronto predefinito per TValue.