VB.NET Language in a Nutshell, Second Edition

Name

Queue Class

Namespace

System.Collections

Createable

Yes

Syntax

Dim queuevariable As [New] Queue

queuevariable (required; Queue object)

The name of the Queue object

Description

A Queue object is a model of a queue. Succinctly put, a queue is a first-in, first-out data structure. (This is often abbreviated FIFO.) Put another way, a queue is a data structure that models a line of items. There is a method for inserting items at the end of the line (enqueueing), as well as a method for removing the item that is currently at the front of the line (dequeueing). Under this scenario, the next item to be dequeued is the item that was placed in line first — hence the term first-in, first-out.

Note that the elements in a Queue object are of type Object.

Queue class members marked with a plus sign (+) are discussed in detail in their own entries.

Public Shared Method

Synchronized

Public Instance Properties

Count +

IsReadOnly

IsSynchronized

SyncRoot

Public Instance Methods

Clone

Contains +

CopyTo +

Dequeue +

Enqueue +

Equals

GetEnumerator

GetHashCode

GetType

Peek +

ToArray +

ToString

Example

Here is a bit of code to illustrate the members of the Queue class:

' Define a new queue Dim q As New Queue( ) ' Queue up some items q.Enqueue("Chopin") q.Enqueue("Mozart") q.Enqueue("Beethoven") ' Is an item in the queue? MsgBox("Beethoven in queue: " & CStr(q.Contains("Beethoven"))) ' Peek at the first item MsgBox("First item in queue is: " & q.Peek.ToString) ' Send queue to an array and display all items Dim s() As Object = q.ToArray( ...