Class dan Object Pada VB [Pertemuan XVI]

Dasar OOP Visual Basic merupakan bahasa yang Object-Based (komponen-komponen program dibuat dalam bentuk objek), sedangkan VB.NET adalah Object Oriented, hal ini berarti bahwa VB.NET merupakan bahasa yang benar-benar berorientasi object dengan mendukung empat pilar utama dari OOP yaitu Polymorphism, Inheritance, Abstraction dan Encapsulation.

Untuk lebih memahami tentang class dan object, kita akan membuat sebuah aplikasi menggunakan class dan object pada pemrograman visual basic 2008

Pertama buat sebuah project baru dengan cara memilih file – new project – new form windows application

Langkah selanjutnya buat sebuah form baru dengan nama Form1 dan desain seperti berikut ini lengkap dengan penamaan pada propertiesnya

Kemudian buat class baru dengan cara berikut ini :

Setelah class telah dibuat langkah selanjutnya adalah mengetikan sintaks berikut ini :

'@desc: 1 : Classes and objects

'================================================================
'Author: Anoop - anoop@logicmatrixonline.com
'        http://www.logicmatrixonline.com/anoop
'================================================================

'LESSON 1: NAMESPACES, CLASSES AND OBJECTS, MODULES
'====================================================

'// 1) A Namespace
'====================================
'
'In VB.NET, classes and other data structures for a specific purpose are
'grouped together to form a namespace.

'You can use the classes in a namespace, by simply importing the namespace.
'The 'imports' keyword is used to import a namespace to your project.
'.NET framework provides a rich set of built in classes, grouped
'to various namespaces.

'In this lesson, we are using the system namespace.



'-----------------------------------------------------------------
'Import the System namespace (already available in .NET)
Imports System
'-----------------------------------------------------------------



'// 2) A Class
'====================================
'
'Probably, you are already familiar with classes and objects
'Simply speaking, a class is a definition of a real life
'object. For example, Human is a class for representing all
'human beings. Dog is a class to represent all Dogs.

'Classes can contain functions too.



'-----------------------------------------------------------------
'Animals is a namespace
Namespace Animals

    'Dog is a class in the namespace Animals
    Class Dog

        'Bark is a function in this class
        Function Bark()
            Console.WriteLine("Dog is barking")
            MsgBox("Dog is barking")
        End Function

    End Class

End Namespace
'-----------------------------------------------------------------



'// 3) An Object
'====================================
'
'An object is an instance of a class. For example,
'Jimmy is an object of type Dog. We will create
'an object in the next section. Read on.


'// 4) Modules
'====================================
'
'You can use modules to write common functions. A module is a
'group of functions. Unlike functions in classes, public functions
'in modules can be called directly from some where else.

'VB provides Functions and Subroutines. Functions and Sub
'routines are almost same, but subroutines can't return
'a value.
'

'-----------------------------------------------------------------


Public Module modMain

    'Execution will start from the Main() subroutine

    Sub Main()

        'Call our function. See below
        OurFunction()
    End Sub


    'OurFunction: Our own little function to use the class Dog

    Function OurFunction()
        'Here is how we declare a variable Jimmy of type Dog.
        'We use Animals.Dog because, the class Dog is in the
        'namespace Animals (see above).

        Dim Jimmy As Animals.Dog

        'Create an object. Unlike in VB 6, it is not required to use
        'the 'set' keyword.

        Jimmy = New Animals.Dog()

        'Another way to create an object is
        'Dim Jimmy as new Dog

        'Call Jimmy's Main Function      
        Jimmy.Bark()

    End Function

End Module

'-----------------------------------------------------------------

Setelah itu, pada Form1.vb ketikan pada btnTampil sintaks berikut ini :

Private Sub btnTampil_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnTampil.Click
        Main()
    End Sub

Sekian Tutorial yang bisa saya berikan untuk teman-teman sekalian, mohon maaf apabila masih banyak kekurangan, semoga tutorial ini bisa bermanfaat bagi yang membutuhkan Aamiin.

Koneksi Database Dalam VB .NET [Pertemuan XV:2]

. 

- Langkah pertama buatlah form lalu design seperti dibawah diatas :

-Lalu masukan code dibawah ini:

Dim cnn As New OleDb.OleDbConnection
    Dim provider As String
    Dim dataFile As String
    Dim connString As String
    Public myConnection As OleDb.OleDbConnection = New OleDb.OleDbConnection
    Public dr As OleDb.OleDbDataReader

*pada button close

Private Sub btnClose_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClose.Click
        Me.Close()
    End Sub

*pada button add

Private Sub btnAdd_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnAdd.Click
        Dim cmd As New OleDb.OleDbCommand
        If Not cnn.State = ConnectionState.Open Then
            'open connection if it is not yet open
            cnn.Open()
        End If

        cmd.Connection = cnn
        'check whether add new or update
        If Me.txtstdID.Tag & "" = "" Then
            'add new 
            'add data to table
            cmd.CommandText = "INSERT INTO student(stdid, stdname, gender, phone, address) " & _
                            " VALUES(" & Me.txtstdID.Text & ",'" & Me.txtStdName.Text & "','" & _
                            Me.cboGender.Text & "','" & Me.txtPhone.Text & "','" & _
                            Me.txtAddress.Text & "')"
            cmd.ExecuteNonQuery()
        Else
            'update data in table
            cmd.CommandText = "UPDATE student " & _
                        " SET stdid=" & Me.txtstdID.Text & _
                        ", stdname='" & Me.txtStdName.Text & "'" & _
                        ", gender='" & Me.cboGender.Text & "'" & _
                        ", phone='" & Me.txtPhone.Text & "'" & _
                        ", address='" & Me.txtAddress.Text & "'" & _
                        " WHERE stdid=" & Me.txtstdID.Tag
            cmd.ExecuteNonQuery()
        End If
        'refresh data in list
        RefreshData()
        'clear form
        Me.btnClear.PerformClick()

        'close connection
        cnn.Close()
    End Sub

*pada button clear

Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
        Me.txtstdID.Text = ""
        Me.txtStdName.Text = ""
        Me.txtPhone.Text = ""
        Me.txtAddress.Text = ""
        Me.txtstdID.Tag = ""
        'enable button edit
        Me.btnEdit.Enabled = True
        'set button add to add label
        Me.btnAdd.Text = "Add"
        '
        Me.txtstdID.Focus()
    End Sub

*pada button edit

Private Sub btnEdit_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEdit.Click
        'check for the selected item in list
        If Me.dgvData.Rows.Count > 0 Then
            If Me.dgvData.SelectedRows.Count > 0 Then
                Dim intStdID As Integer = Me.dgvData.SelectedRows(0).Cells("id").Value
                'get data from database followed by student id
                'open connection
                If Not cnn.State = ConnectionState.Open Then
                    cnn.Open()
                End If
                'get data into datatable
                Dim da As New OleDb.OleDbDataAdapter("SELECT * FROM student " & _
                                                     " WHERE stdid=" & intStdID, cnn)
                Dim dt As New DataTable
                da.Fill(dt)

                Me.txtstdID.Text = intStdID
                Me.txtStdName.Text = dt.Rows(0).Item("stdname")
                Me.cboGender.Text = dt.Rows(0).Item("gender")
                Me.txtPhone.Text = dt.Rows(0).Item("phone")
                Me.txtAddress.Text = dt.Rows(0).Item("address")
                '
                'hide the id to be edited in TAG of txtstdid in case id is changed
                Me.txtstdID.Tag = intStdID
                'change button add to update
                Me.btnAdd.Text = "Update"
                'disable button edit
                Me.btnEdit.Enabled = False
                'close connection
                cnn.Close()
            End If
        End If
    End Sub

*pada button delete

Private Sub btnDelete_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnDelete.Click
        'check for the selected item in list
        If Me.dgvData.Rows.Count > 0 Then
            If Me.dgvData.SelectedRows.Count > 0 Then
                Dim intStdID As Integer = Me.dgvData.SelectedRows(0).Cells("id").Value
                'open connection
                If Not cnn.State = ConnectionState.Open Then
                    cnn.Open()
                End If

                'delete data
                Dim cmd As New OleDb.OleDbCommand
                cmd.Connection = cnn
                cmd.CommandText = "DELETE FROM student WHERE stdid=" & intStdID
                cmd.ExecuteNonQuery()
                'refresh data
                Me.RefreshData()

                'close connection
                cnn.Close()
            End If
        End If
    End Sub

*pada formload

Private Sub frmStudent_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
        cnn = New OleDb.OleDbConnection
        cnn.ConnectionString = "Provider=Microsoft.Jet.Oledb.4.0; Data Source=" & Application.StartupPath & "\data.mdb"
        '
        'get data into list
        Me.RefreshData()
    End Sub

Selmat mencoba.

Cara Menyimpan Dan Membaca Data .txt Di VB [Pertemuan: XV]

Kali ini kita akan membuat program di Visual Basic untuk menyimpan dan membaca file txt. Supaya tidak pusing FS buat program menjadi 2 bagian. Langsung saja!

Contoh Max Min Dan Curah Hujan Pada Visual Basic [Pertemuan: XIII & XIV]

Sebelumnya kita sudah belajar tentang array, dan kali ini kita masih dalam materi array namun dengan sedikit penambahan, yaitu kita akan mempelajari cara mencari max-min, average, dan total pada Array.

Agar materi di atas dapat tersampaikan dan dipahami dengan baik, lakukanlah latihan berikut ini.

Pertama buat sebuah project baru dengan cara memilih file – new project – new form windows application

Cara Membuat MDI Dan Contoh Converter Di Visual Basic [Pertemuan: XII]

Langsung Saja.

1. Buka aplikasi VISUAL BASIC 2010 EXPRESS, lalu setelah program terbuka, klik FILE > New Project, maka akan muncul windows pop-up, lalu pilih “Windows Form Application”. Jika sudah di pilih isikan Nama dan Tempat Penyimpan project yang nanti akan di buat pada Name dan Location jika sudah klik Ok.