Public Class Form1
'初始化一个实例
Private Sub InitiCustomer()
Dim objCustomer As Customer
objCustomer.FirstName = "Michael"
objCustomer.LastName = "Dell"
objCustomer.Email = "mdell@somecompany.com"
DisplayCustomer(objCustomer)
End Sub
'显示一个实例
Private Sub DisplayCustomer(ByVal customer As Customer)
txtName.Text = customer.name
txtFirstName.Text = customer.FirstName
txtLastName.Text = customer.LastName
txtEmail.Text = customer.Email
End Sub
'创建一个Customer结构对象实例
Public Sub CreaterCustomer( _
ByVal FirstName As String, _
ByVal LastName As String, _
ByVal Email As String _
)
Dim objNewCustomer As Customer
objNewCustomer.FirstName = FirstName
objNewCustomer.LastName = LastName
objNewCustomer.Email = Email
'列表或集合中添加一个新对象
objCustomers.Add(objNewCustomer)
lstCustomers.Items.Add(objNewCustomer)
End Sub
'被选元素的属性
Public ReadOnly Property SelectCustomer() As Customer
Get
If lstCustomers.SelectedIndex <> -1 Then
Return objCustomers(lstCustomers.SelectedIndex)
End If
End Get
End Property
'创建一个列表
'Private objCustomers As New ArrayList
'创建一个集合
Private objCustomers As New CustomerCollection
'列表按钮
Private Sub btnListCustomer_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnListCustomer.Click
objCustomers.clear()
lstCustomers.Items.Clear()
'参数表为firstname,lastname,Email
CreaterCustomer("a1", "a2", "a@163.com")
CreaterCustomer("b1", "b2", "b@163.com")
CreaterCustomer("c1", "c2", "c@163.com")
End Sub
'删除按钮
Private Sub BtnDeleteCustomer_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles BtnDeleteCustomer.Click
If lstCustomers.SelectedIndex = -1 Then
MessageBox.Show("You must Selet a Customer to Delete.", "Structure Demo")
Exit Sub
End If
If MessageBox.Show("Are you sure?", "Structure Demo", MessageBoxButtons.YesNo, MessageBoxIcon.Warning) = Windows.Forms.DialogResult.Yes Then
Dim objCustomerToDelete As Customer = SelectCustomer
objCustomers.Remove(objCustomerToDelete)
lstCustomers.Items.Remove(objCustomerToDelete)
End If
End Sub
Private Sub lstCustomers_SelectedIndexChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles lstCustomers.SelectedIndexChanged
DisplayCustomer(SelectCustomer)
End Sub
Private Sub btnLookup_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnLookup.Click
Dim objFoundcustomer As Customer = objCustomers(txtEmail.Text)
If Not IsNothing(objFoundcustomer.Email) Then
MessageBox.Show("The customer name is:" & objFoundcustomer.name, "Structuse Demo")
Else
MessageBox.Show("There is no customer with the email" & "address" & txtEmail.Text & ".", "structure Demo")
End If
End Sub
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
InitiCustomer()
End Sub
End Class
-------------------------------
Customer结构
Public Structure Customer
Public FirstName As String
Public LastName As String
Public Email As String
Public ReadOnly Property name() As String
Get
Return FirstName & "·" & LastName
End Get
End Property
'结构的ToString方法默认返回结构名，所以要重写ToString方法
Public Overrides Function ToString() As String
Return name & ", Email:" & Email
End Function
End Structure
——————————————————————————————————————
Customer集合
Public Class CustomerCollection
Inherits CollectionBase
Private objEmailHashtable As New Hashtable
Public ReadOnly Property EmailHashtable() As Hashtable
Get
Return objEmailHashtable
End Get
End Property
Default Public Property item(ByVal index As Integer) As Customer
Get
Return CType(Me.List.Item(index), Customer)
End Get
Set(ByVal value As Customer)
Me.List.Item(index) = value
End Set
End Property
Default Public ReadOnly Property item(ByVal email As String) As Customer
Get
Return CType(EmailHashtable.Item(email.ToLower), Customer)
End Get
End Property
'添加
Public Sub Add(ByVal newCustomer As Customer)
Me.List.Add(newCustomer)
EmailHashtable.Add(newCustomer.Email.ToLower, newCustomer)
End Sub
'删除
Public Sub Remove(ByVal oldcustomer As Customer)
Me.List.Remove(oldcustomer)
EmailHashtable.Remove(oldcustomer.Email.ToLower)
End Sub
Public Shadows Sub removeAt(ByVal index As Integer)
Remove(item(index))
End Sub
Public Shadows Sub clear()
MyBase.OnClear()
EmailHashtable.Clear()
End Sub
End Class