类的继承学习笔记

最新推荐文章于 2025-12-18 16:14:31 发布

原创最新推荐文章于 2025-12-18 16:14:31 发布 · 630 阅读

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#string #function #class #button #less

本文通过一个具体的示例展示了面向对象编程中继承与多态的概念。示例中定义了一个基本的Account类，并在此基础上创建了SavingsAccount子类，实现了特定的方法覆盖，如余额扣减、显示账户信息及计算银行费用等。

Public MustInherit Class Account

Private Name As String
Protected Balance As Double

    Public Sub New(ByVal Nm As String, ByVal Bal As Double)
        Name = Nm
        Balance = Bal
    End Sub

    Public Overridable Sub Credit(ByVal Amount As Double)
        Balance = Amount
    End Sub

    Public Overridable Sub Debit(ByVal Amount As Double)
        Balance = Amount
    End Sub

    Public Overridable Sub Display()
        MessageBox.Show("name " & Name & "Money " & Balance)
    End Sub

    Public Sub ChangeName(ByVal newName As String)
        Name = newName
    End Sub

Public MustOverride Function CalculateBankcharge() As Double
End Class
-----------------------------------------------------------------------------------------------

Public Class SavingsAccount
Inherits Account

Private MinBalance As Double

    Public Sub New(ByVal Nm As String, ByVal Bal As Double, ByVal Min As Double)
        MyBase.new(Nm, Bal)
        MinBalance = Min
    End Sub

    Public Overrides Sub Debit(ByVal Amount As Double)
        If Amount <= Balance Then
            MyBase.Debit(Amount)
        End If
    End Sub

    Public Overrides Sub Display()
        MyBase.Display()
        MessageBox.Show("give me 5,beacouse :" & MinBalance & "less")
    End Sub

    Public Overrides Function CalculateBankcharge() As Double
        If balance < MinBalance Then
            Return 5.0
        Else
            Return 0.0
        End If
    End Function
End Class
-------------------------------------------------------------------------------------------------------------

    Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
        Dim sa As New SavingsAccount("me", 100.0, 25)
        sa.Display()

        sa.Credit(100)
        sa.Debit(180)
        sa.ChangeName("zhang lei")
        sa.Display()
        MessageBox.Show(sa.CalculateBankcharge())
    End Sub