ConcurrentDictionary<TKey,TValue>.TryRemove Metoda

Definice

Obor názvů:

System.Collections.Concurrent

Sestavení:

netstandard.dll, System.Collections.Concurrent.dll

Přetížení

Name	Description
TryRemove(TKey, TValue)	Pokusí se odebrat a vrátit hodnotu, která má zadaný klíč z objektu ConcurrentDictionary<TKey,TValue>.
TryRemove(KeyValuePair<TKey,TValue>)	Odebere klíč a hodnotu ze slovníku.

TryRemove(TKey, TValue)

Zdroj:

ConcurrentDictionary.cs

Pokusí se odebrat a vrátit hodnotu, která má zadaný klíč z objektu 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

Parametry

key

TKey

Klíč elementu, který chcete odebrat a vrátit.

value

TValue

Pokud tato metoda vrátí, obsahuje objekt odebraný z ConcurrentDictionary<TKey,TValue>, nebo výchozí hodnota TValue typu, pokud key neexistuje.

Návraty

Boolean

truepokud byl objekt úspěšně odebrán; v opačném případě . false

Výjimky

ArgumentNullException

key je null.

Příklady

Následující příklad ukazuje, jak volat metodu ConcurrentDictionary<TKey,TValue>.TryRemove :

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

Viz také

• Thread-Safe kolekce
• Postupy: Přidávání a odebírání položek ze slovníku ConcurrentDictionary

TryRemove(KeyValuePair<TKey,TValue>)

Zdroj:

ConcurrentDictionary.cs

Odebere klíč a hodnotu ze slovníku.

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

Parametry

item

KeyValuePair<TKey,TValue>

Představuje KeyValuePair<TKey,TValue> klíč a hodnotu, které chcete odebrat.

Návraty

Boolean

true pokud je klíč a hodnota reprezentované item úspěšně nalezeny a odebrány; v opačném případě false.

Výjimky

ArgumentNullException

Key vlastnost item je null.

Poznámky

Specifikovaný klíč i hodnota musí odpovídat položce ve slovníku, aby byla odebrána.

Klíč se porovná pomocí porovnávače slovníku (nebo výchozího porovnávače, pokud TKey nebyl do slovníku zadán žádný porovnávač, když byl vytvořen). Hodnota se porovnává pomocí výchozího porovnávače pro TValue.