学习泛型

Imports System.Collections.Generic

Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        '定义客户对象
        Dim Customers As New List(Of Customer)
        Dim custA As New Customer("老虎", 1000)
        Dim custB As New Customer("豹子", 2000)

        Customers.Add(custA)
        Customers.Add(custB)

        '输出客户信息
        For Each c As Customer In Customers
            Response.Write("用户名: " & c.Name & ", 贷款额度: " & c.CreditLimit.ToString + "<br>")
        Next

        '实现比较
        Dim cc As New Comparer(Of Customer)
        Dim lc As Customer = cc.GetLargest(custA, custB)
        Response.Write("贷款额度较高的客户：" & lc.Name + "<br>")

        '定义产品对象
        Dim Products As New List(Of Product)
        Dim prod1 As New Product("老虎", 10)
        Dim prod2 As New Product("豹子", 100)

        Products.Add(prod1)
        Products.Add(prod2)

        '输出产品信息
        For Each p As Product In Products
            Response.Write("产品名称：" & p.Name & ",产品价格：" & p.Price.ToString + "<br>")
        Next

        '实现比较
        Dim pc As New Comparer(Of Product)
        Dim lp As Product = pc.GetLargest(prod1, prod2)
        Response.Write("产品价格较高的是：" & lp.Name + "<br>")

    End Sub

    '客户类
    Public Class Customer
        Implements IComparable

        '客户名称
        Public Name As String
        '贷款额度
        Public CreditLimit As Decimal

        Public Sub New(ByVal CustomerName As String, ByVal CustCreditLimit As Decimal)
            Name = CustomerName
            CreditLimit = CustCreditLimit
        End Sub

        '实现IComparable接口的比较方法
        Public Function CompareTo(ByVal obj As Object) As Integer Implements IComparable.CompareTo
            Dim c As Customer = CType(obj, Customer)
            If CreditLimit > c.CreditLimit Then Return 1
            If CreditLimit < c.CreditLimit Then Return -1
            Return 0
        End Function
    End Class

    '产品类
    Public Class Product
        Implements IComparable

        '产品名称
        Public Name As String
        '产品价格
        Public Price As Decimal

        Public Sub New(ByVal _Name As String, ByVal _Price As Decimal)
            Name = _Name
            Price = _Price
        End Sub

        '实现IComparable接口的比较方法
        Public Function CompareTo(ByVal obj As Object) As Integer Implements IComparable.CompareTo
            Dim c As Product = CType(obj, Product)
            If Price > c.price Then Return 1
            If Price < c.Price Then Return -1
            Return 0
        End Function
    End Class

    '对象比较类，泛型实现
    Public Class Comparer(Of itemType As IComparable)

        '取二者之中较大的一个
        Public Function GetLargest(ByVal Item1 As itemType, ByVal Item2 As itemType) As itemType
            Dim i As Integer = Item1.CompareTo(Item2)
            If i > 0 Then Return Item1
            If i < 0 Then Return Item2
            Return Nothing
        End Function
    End Class
End Class