What is the most suitable way to solve the problem?

Question

I am a VB begainer, and I have a question for storing data: I have designed a form which is a calculator for scoring marks, because it is a practice from my school so there are some rules for the calculator, it has to save a name in the listbox every time that the record is confirm which is I have already done.
And I want to store those records into an array or some functions that I can store temporary and retrieve later. Is there any functions in VB can virtulize?

Answer 1

Hello @HO Kwok Piu (200257110) ,

A simplistic solution if the intent is to remember information between sessions and quick-n-easy way is to use a json file. Note there are other options e.g. saving to a text delimited file or xml while the following is strongly typed and a better solution.

In the following GitHub repository I've created a conceptual/working code sample meaning it demonstrates reading/writing to the json file and has comments.
https://github.com/karenpayneoregon/visual-basic-getting-started/tree/master/BasicJson_1

[  
  {  
    "Name": "First item",  
    "Value": 11.34  
  },  
  {  
    "Name": "Secondt item",  
    "Value": 1.33  
  }  
]  

Class for storing data

Imports System.ComponentModel  
Imports System.Runtime.CompilerServices  
  
Namespace Classes  
    Public Class ApplicationStorage  
        Implements INotifyPropertyChanged  
        Private _name As String  
        Private _value As Decimal  
  
        Public Property Name() As String  
            Get  
                Return _name  
            End Get  
            Set  
                _name = value  
                OnPropertyChanged()  
            End Set  
        End Property  
  
        Property Value() As Decimal  
            Get  
                Return _value  
            End Get  
            Set  
                _value = value  
                OnPropertyChanged()  
            End Set  
        End Property  
  
        Public Overrides Function ToString() As String  
            Return Name  
        End Function  
        Public Event PropertyChanged As PropertyChangedEventHandler Implements INotifyPropertyChanged.PropertyChanged  
        Protected Overridable Sub OnPropertyChanged(<CallerMemberName> Optional memberName As String = Nothing)  
            RaiseEvent PropertyChanged(Me, New PropertyChangedEventArgs(memberName))  
        End Sub  
    End Class  
End Namespace  

File operations class

Imports System.IO  
Imports Newtonsoft.Json  
  
Namespace Classes  
    Public Class FileOperations  
        Public Shared FileName As String = "appSetting.json"  
        Public Shared Sub Save(storageList As List(Of ApplicationStorage))  
            Using streamWriter = File.CreateText(FileName)  
  
                Dim serializer = New JsonSerializer With {.Formatting = Formatting.Indented}  
                serializer.Serialize(streamWriter, storageList)  
  
            End Using  
  
        End Sub  
        Public Shared Function Load() As List(Of ApplicationStorage)  
  
            Using streamReader = New StreamReader(FileName)  
                Dim json = streamReader.ReadToEnd()  
                Return JsonConvert.DeserializeObject(Of List(Of ApplicationStorage))(json)  
            End Using  
  
        End Function  
  
    End Class  
End Namespace  

Form code

Imports System.ComponentModel  
Imports System.IO  
Imports BasicJson_1.Classes  
  
Public Class Form1  
    ''' <summary>  
    ''' Storage container for ApplicationStorage data.  
    ''' Using a BindingList and implementing INotifyPropertyChanged interface  
    ''' permits real time updates to ListBox.  
    ''' </summary>  
    Private bindingList as new BindingList(Of ApplicationStorage)  
    ''' <summary>  
    ''' Load from file if exists  
    ''' </summary>  
    ''' <param name="sender"></param>  
    ''' <param name="e"></param>  
    Private Sub Form1_Shown(sender As Object, e As EventArgs) Handles Me.Shown  
  
        If File.Exists(FileOperations.FileName) Then  
  
            Try  
                bindingList = New BindingList(Of ApplicationStorage)(FileOperations.Load())  
            Catch ex As Exception  
                MessageBox.Show($"Failed to load json{Environment.NewLine}{ex.Message}")  
            End Try  
        End If  
  
        ListBox1.DataSource = bindingList  
  
    End Sub  
  
    ''' <summary>  
    ''' Add new item if name is value and a valid decimal was entered  
    ''' </summary>  
    ''' <param name="sender"></param>  
    ''' <param name="e"></param>  
    Private Sub AddButton_Click(sender As Object, e As EventArgs) Handles AddButton.Click  
        Dim value as Decimal = 0  
  
        if Decimal.TryParse(ValueTextBox.Text, value) AndAlso Not string.IsNullOrWhiteSpace(NameTextBox.Text)  
            bindingList.Add(new ApplicationStorage() With{.Name = NameTextBox.Text, .Value = value})  
        End If  
  
    End Sub  
    ''' <summary>  
    ''' Save items to json  
    ''' </summary>  
    ''' <param name="sender"></param>  
    ''' <param name="e"></param>  
    Private Sub SaveAllButton_Click(sender As Object, e As EventArgs) Handles SaveAllButton.Click  
        if bindingList.Count >0  
            FileOperations.Save(bindingList.ToList())  
        End If  
    End Sub  
    ''' <summary>  
    ''' Get current item  
    ''' </summary>  
    ''' <param name="sender"></param>  
    ''' <param name="e"></param>  
    Private Sub CurrentButtonButton_Click(sender As Object, e As EventArgs) Handles CurrentButton.Click  
        if bindingList.Count >0  
            if ListBox1.SelectedIndex > -1  
                Dim currentItem = bindingList.Item(ListBox1.SelectedIndex)  
                MessageBox.Show($"Name: {currentItem.Name} Value: {currentItem.Value}")  
            End If  
        End If  
  
    End Sub  
End Class  

Screen shot

Answer 2

Hi

A simple example - Karens post is much more detailed.

Option Strict On
Option Explicit On
Public Class Form1
' crrate the datatable variable
Dim dt As New DataTable("MyTable")

         ' make a path to store/retrieve data
         ' here, using a system method to make
         ' the path in a safe way (to the DeskTop)
         Dim path As String = IO.Path.Combine(My.Computer.FileSystem.SpecialDirectories.Desktop, "MyDataTableData.xml")
         Private Sub Form1_FormClosing(sender As Object, e As FormClosingEventArgs) Handles Me.FormClosing
             ' every time you close the application
             ' the datatable data will be saved.
             dt.WriteXml(path)
         End Sub
         Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
             With dt
                 ' create the columns required in
                 ' the datatable
                 .Columns.Add("ID", GetType(Integer))
                 .Columns.Add("Name", GetType(String))
                 .Columns.Add("Date", GetType(DateTime))
                 .Columns.Add("Other", GetType(String))
                 .Columns.Add("Notes", GetType(String))

                 If IO.File.Exists(path) Then
                     ' found a datafile, so read it into
                     ' the datatable
                     .ReadXml(path)
                 End If
             End With
             ' put the data into a DataGridView
             ' where changes made will be reflected
             ' in the datatable - keeping everything
             ' in sync.
             DataGridView1.DataSource = dt
         End Sub
     End Class

Answer 3

Hallo All, Which is faster for reading data into program XML or Jason ? any difference?

Answer 4

Hi
Using XML or JSON for storage should have minimal difference. If you are dealing with huge amounts of data then there may be some small difference.
You could mock up a test for each using the same data and use a timing loop to check on timings.

Answer 5

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