Stack.Synchronized Method (Stack)

 

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

Namespace:   System.Collections
Assembly:  mscorlib (in mscorlib.dll)

<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.

Exception Condition
ArgumentNullException

stack is null.

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.

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.

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
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