vb.net – 使用Inherited One时传递基础对象类型

发布时间：2020-12-17 07:23:39 所属栏目：百科来源：网络整理

导读：我有一个项目,主要有两个对象,都从一个基础继承.像这样： Public Class Vehicle Property Model As String Property Make As StringEnd ClassPublic Class Truck Inherits Vehicle Property IsFlatbed As BooleanEnd ClassPublic Class Car Inherits Vehicle

我有一个项目,主要有两个对象,都从一个基础继承.像这样：

Public Class Vehicle
    Property Model As String
    Property Make As String
End Class

Public Class Truck
    Inherits Vehicle
    Property IsFlatbed As Boolean
End Class

Public Class Car
    Inherits Vehicle
    Property LeatherSeats As Boolean
End Class

很简单,嗯？因为我不知道用户是选择汽车还是卡车,我想做的只是绕过车辆.

所以,像这样：

Public v As Vehicle
Sub WhichVehicle()
    Select Case cmbVehicle.SelectedItem
        Case Truck
            v = New Truck
        Case Car
            v = New Car
    End Select
    SetFlat (v)
End Sub

这一切都有效,但现在我只想通过v并使用它的属性.喜欢：

Sub SetFlat (myVehicle As Vehicle)
    myVehicle.IsFlatbed = True
End Sub

上述功能不起作用,因为myVehicle是一辆车,而不是卡车.

有没有办法可以传递一种车辆类型并让IDE知道要使用哪种类型？或者我完全错过了更好的方法吗？

解决方法

这是您可以实现此目的的一种方式：

Imports System.Reflection
Module main_
    Sub Main()
        Dim t As New Truck
        Dim c As New Car
        Dim v As Vehicle
        v = t
        SetFlat(v)
        v = c
        SetFlat(v)
    End Sub
    Sub SetFlat(ByVal v As Vehicle)

        Dim vehicletype As Type
        Dim members() As PropertyInfo

        vehicletype = v.GetType
        members = vehicletype.GetProperties

        Console.Write("v is a " & vehicletype.ToString)
        For Each m As PropertyInfo In members
            If m.Name = "IsFlatbed" Then
                m.SetValue(v,True,Nothing)
                Console.WriteLine(" and now it's a flatbed")
                Exit Sub
            End If
        Next
        Console.WriteLine(" so flatbed doesn't apply")
    End Sub
End Module

输出：

v is a Vehicles.Truck and now it's a flatbed
v is a Vehicles.Car so flatbed doesn't apply

（编辑：李大同）

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