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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
Public Shared Function Synchronized ( _
	stack As Stack _
) As Stack
'Usage
Dim stack As Stack
Dim returnValue As Stack

returnValue = Stack.Synchronized(stack)
public static Stack Synchronized (
	Stack stack
)
public static function Synchronized (
	stack : Stack
) : Stack
Not applicable.

Parameters

stack

The Stack to synchronize.

Return Value

A synchronized wrapper around the Stack.

Exception typeCondition

ArgumentNullException

stack is a null reference (Nothing in Visual Basic).

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()
 Dim item As Object
 SyncLock myCollection.SyncRoot
  For Each item 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.
 

import System.*;
import System.Collections.*;

public class SamplesStack
{
    public static void main(String[] args)
    {
        // Creates and initializes a new Stack.
        Stack myStack = new Stack();

        myStack.Push("The");
        myStack.Push("quick");
        myStack.Push("brown");
        myStack.Push("fox");

        // Creates a synchronized wrapper around the Stack.
        Stack mySyncdStack = Stack.Synchronized(myStack);

        // Displays the sychronization status of both Stacks.
        Console.WriteLine("myStack is {0}.", 
            (myStack.get_IsSynchronized()) ? 
            "synchronized" : "not synchronized");
        Console.WriteLine("mySyncdStack is {0}.", 
            (mySyncdStack.get_IsSynchronized()) ? 
            "synchronized" : "not synchronized");
    } //main

} //SamplesStack

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

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

XNA Framework

Supported in: 1.0

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