Queue类代表了先入先出的对象集合。它用于需要先进先出访问项目的情况。当在列表中添加一个项目时称为入队，当删除一个项目时称为出队。
Queue类的属性和方法
下表列出了Queue类的一些常用属性：
| 编号 | 属性 | 描述 |
|---|---|---|
| 1 | Count |
获取队列中包含的元素的数量。 |
下表列出了Queue类的一些常用方法：
| 编号 | 方法 | 描述 |
|---|---|---|
| 1 | Public Overridable Sub Clear |
删除堆栈中的所有元素。 |
| 2 | Public Overridable Function Contains (obj As Object) As Boolean |
确定元素是否在队列中。 |
| 3 | Public Overridable Function Dequeue As Object |
删除并返回队列开始处的对象。 |
| 4 | Public Overridable Sub Enqueue (obj As Object) |
将一个对象添加到队列的末尾。 |
| 5 | Public Overridable Function ToArray As Object() |
将队列复制到新数组。 |
| 6 | Public Overridable Sub TrimToSize |
将容量设置为队列中实际元素的数量。 |
实例
以下示例演示如何使用队列：
Imports System.Collections
Module MyQueue
Sub Main()
Dim q As Queue = New Queue()
q.Enqueue("A")
q.Enqueue("M")
q.Enqueue("G")
q.Enqueue("W")
Console.WriteLine("Current queue: ")
Dim c As Char
For Each c In q
Console.Write(c + " ")
Next c
Console.WriteLine()
q.Enqueue("V")
q.Enqueue("H")
Console.WriteLine("Current queue: ")
For Each c In q
Console.Write(c + " ")
Next c
Console.WriteLine()
Console.WriteLine("Removing some values ")
Dim ch As Char
ch = q.Dequeue()
Console.WriteLine("The removed value: {0}", ch)
ch = q.Dequeue()
Console.WriteLine("The removed value: {0}", ch)
Console.ReadKey()
End Sub
End Module
执行上面示例代码，得到以下结果 -
F:\worksp\vb.net\collection>vbc MyQueue.vb
Microsoft (R) Visual Basic Compiler version 14.0.1038
for Visual Basic 2012
Copyright (c) Microsoft Corporation. All rights reserved.
This compiler is provided as part of the Microsoft (R) .NET Framework, but only supports language versions up to Visual Basic 2012, which is no longer the latest version. For compilers that support newer versions of the Visual Basic programming language, see http://go.microsoft.com/fwlink/?LinkID=533241
F:\worksp\vb.net\collection>MyQueue.exe
Current queue:
A M G W
Current queue:
A M G W V H
Removing some values
The removed value: A
The removed value: M