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Stack.Synchronized Method

Returns a synchronized (thread safe) wrapper for the Stack.

Namespace:  System.Collections
Assembly:  mscorlib (in mscorlib.dll)
'Declaration
<HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization := True)> _
Public Shared Function Synchronized ( _
	stack As Stack _
) As Stack

Parameters

stack
Type: System.Collections.Stack

The Stack to synchronize.

Return Value

Type: System.Collections.Stack
A synchronized wrapper around the Stack.
ExceptionCondition
ArgumentNullException

stack is Nothing.

To guarantee the thread safety of the Stack, all operations must be done through this wrapper.

Enumerating through a collection is intrinsically not a thread-safe procedure. Even when a collection is synchronized, other threads can still modify the collection, which causes the enumerator to throw an exception. To guarantee thread safety during enumeration, you can either lock the collection during the entire enumeration or catch the exceptions resulting from changes made by other threads.

The following code example shows how to lock the collection using the SyncRoot during the entire enumeration.

Dim myCollection As New Stack()

SyncLock myCollection.SyncRoot
    For Each item As Object In myCollection
        ' Insert your code here. 
    Next item
End SyncLock

This method is an O(1) operation.

NoteNote

The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: Synchronization. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.

The following example shows how to synchronize a Stack, determine if a Stack is synchronized, and use a synchronized Stack.

Imports System
Imports System.Collections

Public Class SamplesStack    

    Public Shared Sub Main()

        ' Creates and initializes a new Stack. 
        Dim myStack As New Stack()
        myStack.Push("The")
        myStack.Push("quick")
        myStack.Push("brown")
        myStack.Push("fox")

        ' Creates a synchronized wrapper around the Stack. 
        Dim mySyncdStack As Stack = Stack.Synchronized(myStack)

        ' Displays the sychronization status of both Stacks. 
        Dim msg As String 
        If myStack.IsSynchronized Then
            msg = "synchronized" 
        Else
            msg = "not synchronized" 
        End If        
        Console.WriteLine("myStack is {0}.", msg)        
        If mySyncdStack.IsSynchronized Then
            msg = "synchronized" 
        Else
            msg = "not synchronized" 
        End If
        Console.WriteLine("mySyncdStack is {0}.", msg)
    End Sub 
End Class 

' This code produces the following output. 
'  
' myStack is not synchronized. 
' mySyncdStack is synchronized.

.NET Framework

Supported in: 4.5.1, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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