Cara Mencari Luas Lingkatan dan Segitiga dengan Visual Basic

Disini saya mendapatkan tugas dari asisten praktikum visual basic saya, berikut       

 soalnya:

            Buat kelas abstrak Shape dengan sebuah method abstrak bernama GetArea(). Definisikan juga dua subkelas dari Shape dengan nama Rectangle dan Circle. Gunakan rumus penghitungan luas untuk mengimplementasikan method GetArea().

Code:

Public Class circle

    Inherits shape

    Dim radius As Double

    Const phi = 3.14

    Sub New(ByVal r As Decimal)

        radius = r

    End Sub

    Public Overrides Function getArea() As Double

        area = phi * (radius * radius)

        Return area

    End Function

End Class

                                  

Public Class rectangle

    Inherits shape

    Dim panjang As Decimal

    Dim lebar As Decimal

    Sub New(ByVal l As Double, ByVal w As Double)

        panjang = l

        lebar = w

    End Sub

    Public Overrides Function getArea() As Double

        area = panjang * lebar

        Return area

    End Function

End Class

Public MustInherit Class shape

    Protected area As Double

    Public MustOverride Function getArea() As Double

End Class

Public Class Form1

    Function lingkaran(ByVal jari2)

        Dim myCircle As New circle(jari2)

        Dim hasil As Double

        hasil = myCircle.getArea

        Return hasil

    End Function

    Function persegi(ByVal pj, ByVal lb)

        Dim myRectangle As New rectangle(pj, lb)

        Dim hasil As Double

        hasil = myRectangle.getArea

        Return hasil

    End Function

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

        TextBox2.Text = CStr(lingkaran(CInt(TextBox1.Text)))

    End Sub

    Private Sub Button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button2.Click

        TextBox5.Text = CStr(persegi(CInt(TextBox3.Text), CInt(TextBox4.Text)))

    End Sub

End Class

Hasil screenn shot: