Represents a first-in, first-out collection of objects.
Assembly: System (in System.dll)
Queues are useful for storing messages in the order they were received for sequential processing. Objects stored in a are inserted at one end and removed from the other.
The capacity of a is the number of elements the can hold. As elements are added to a , the capacity is automatically increased as required by reallocating the internal array. The capacity can be decreased by calling TrimExcess.
accepts a null reference (Nothing in Visual Basic) as a valid value for reference types and allows duplicate elements.
The following code example demonstrates several methods of the generic class. The code example creates a queue of strings with default capacity and uses the Enqueue method to queue five strings. The elements of the queue are enumerated, which does not change the state of the queue. The Dequeue method is used to dequeue the first string. The Peek method is used to look at the next item in the queue, and then the Dequeue method is used to dequeue it.
The ToArray method is used to create an array and copy the queue elements to it, then the array is passed to the Queue(T) constructor that takes IEnumerable(T), creating a copy of the queue. The elements of the copy are displayed.
An array twice the size of the queue is created, and the CopyTo method is used to copy the array elements beginning at the middle of the array. The Queue(T) constructor is used again to create a second copy of the queue containing three null elements at the beginning.
Public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
A can support multiple readers concurrently, as long as the collection is not modified. Even so, enumerating through a collection is intrinsically not a thread-safe procedure. To guarantee thread safety during enumeration, you can lock the collection during the entire enumeration. To allow the collection to be accessed by multiple threads for reading and writing, you must implement your own synchronization.
Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune
The .NET Framework and .NET Compact Framework do not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.