VB.NET 物件導向 Class.2 (類別安全性+多型+迴圈)

類別基本練習：類別安全性

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Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click

        Dim car1 As New Car
        Dim pN As Integer = InputBox("輸入車牌")
        Dim cN As String = InputBox("輸入車款")
        Dim g As Double = InputBox("輸入排氣量")

        If car1.setData(pN, cN, g) = True Then       //先帶入值檢驗是否合法
            car1.Car(pN, cN, g)                                  //合法就帶入值
            car1.show()                                               //並秀出來
        Else
            MessageBox.Show("輸入錯誤請重新執行")
        End If

    End Sub
End Class
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Class Car
    Dim pNum As Integer
    Dim cName As String
    Dim gas As Integer
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//帶入檢驗合格的值
    Sub Car(pN, cN, g)
        pNum = pN
        cName = cN
        gas = g
    End Sub
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//帶入值檢驗是否合格
    Function setData(pN, cN, g)
        Dim result As Boolean = True
        If g < 0 Then
            result = False
        End If
        Return result
    End Function
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//內呼叫方法
    Sub show()
        ShowData()
    End Sub
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    Private Sub ShowData()
        MessageBox.Show("車牌號碼：" & pNum & vbCr &
                        "車款：" & cName & vbCr &
                        "排氣量：" & gas)
    End Sub
End Class

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多型：
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Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim car1 As New Car
        Dim pN As Integer = InputBox("輸入車牌")
        Dim cN As String = InputBox("輸入車款")
        Dim g As Double = InputBox("輸入排氣量")
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//全部設定
        car1.setData(pN, cN, g)
        car1.showData()
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//只改車牌
        pN = InputBox("輸入車牌")
        car1.setData(pN)
        car1.showData()
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//只改車款&排氣量
        cN = InputBox("輸入車款")
        g = InputBox("輸入排氣量")
        car1.setData(cN, g)
        car1.showData()

    End Sub
End Class
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Class Car
    Dim pNum As Integer
    Dim cName As String
    Dim gas As Integer
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//方法相同傳入值不同有不同處理方法
    Sub setData(pN)
        pNum = pN
    End Sub
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    Sub setData(cN, g)
        cName = cN
        gas = g
    End Sub
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    Sub setData(pN, cN, g)
        pNum = pN
        cName = cN
        gas = g
    End Sub
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    Sub showData()
        MessageBox.Show("車牌號碼：" & pNum & vbCr &
                        "車款：" & cName & vbCr &
                        "排氣量：" & gas)
    End Sub

End Class

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迴圈：
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Public Class Form1

    Private Sub Button1_Click(sender As System.Object, e As System.EventArgs) Handles Button1.Click
        Dim car1 As New Car
        Dim pN As Integer
        Dim cN As String
        Dim g As Double
        Dim i As Integer
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//就只是迴圈
        For i = 1 To 5
            MessageBox.Show("請輸入第 " & i & " 輛車資料")
            pN = InputBox("輸入車牌")
            cN = InputBox("輸入車款")
            g = InputBox("輸入排氣量")
            If g < 0 Then
                i -= 1
                Continue For
            Else
                car1.setData(pN, cN, g)
                car1.showData()
            End If
        Next
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    End Sub
End Class
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Class Car
    Dim pNum As Integer
    Dim cName As String
    Dim gas As Double
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    Sub setData(pN, cN, g)
        pNum = pN
        cName = cN
        gas = g
    End Sub
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    Sub showData()
        MessageBox.Show("車牌號碼：" & pNum & vbCr &
                        "車款：" & cName & vbCr &
                        "排氣量：" & gas)
    End Sub

End Class

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