Synchronized Method

Queue.Synchronized Method (Queue)


Returns a new Queue that wraps the original queue, and is thread safe.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, Synchronization = true)]
public static Queue Synchronized(
	Queue queue


Type: System.Collections.Queue

The Queue to synchronize.

Return Value

Type: System.Collections.Queue

A Queue wrapper that is synchronized (thread safe).

Exception Condition

queue is null.

The wrapper returned by this method locks the queue before an operation is performed so that it is performed in a thread-safe manner.

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

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. This method is an O(1) operation.

Queue myCollection = new Queue();
    foreach (object item in myCollection)
        // Insert your code here.

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

using System;
using System.Collections;
public class SamplesQueue  {

   public static void Main()  {

      // Creates and initializes a new Queue.
      Queue myQ = new Queue();
      myQ.Enqueue( "The" );
      myQ.Enqueue( "quick" );
      myQ.Enqueue( "brown" );
      myQ.Enqueue( "fox" );

      // Creates a synchronized wrapper around the Queue.
      Queue mySyncdQ = Queue.Synchronized( myQ );

      // Displays the sychronization status of both Queues.
      Console.WriteLine( "myQ is {0}.", myQ.IsSynchronized ? "synchronized" : "not synchronized" );
      Console.WriteLine( "mySyncdQ is {0}.", mySyncdQ.IsSynchronized ? "synchronized" : "not synchronized" );
This code produces the following output.

myQ is not synchronized.
mySyncdQ is synchronized.

Universal Windows Platform
Available since 10
.NET Framework
Available since 1.1
Return to top
© 2015 Microsoft