Multithreading in Visual Basic.NET: Demo

Category:

C#, VB.NET, ASP.NET

Type:

Applications

Difficulty:

Advanced

Author:

Pramod Kumar Singh

Version Compatibility: Visual Basic.NET

More information:

The sample code demonstrates multithreading in VB.NET. The application creates two threads that are accesing the same account amount.This reqires synchronization of threads, which is accomplished in VB.NET through use of the Monitor object of the the Thread class.

To run this code, create a new Console application in Visual Basic.NET, paste the code into the code window, right click the project name and select project properties, and change the startup object to Thread Sample.

Instructions: Copy the declarations and code below and paste directly into your VB project.

Declarations:
' (None)

Code:

Imports System
Imports System.Threading
Public Module ThreadSample
    Public Balance As Integer = 1000
    Sub Main()
        Dim account As Account = New Account()
        Dim depositeBalance1 As DepositeBalance = New _
                DepositeBalance(account, 1000, "Customer 1")
        Dim depositeBalance2 As DepositeBalance = New _
           DepositeBalance(account, 1000, "Customer 2")
        Dim t1 As Thread = New _
             Thread(AddressOf depositeBalance1.DepositeAmount)
        Dim t2 As Thread = New _
        Thread(AddressOf depositeBalance2.DepositeAmount)
        t1.Start()
        t2.Start()
        Try
            t1.Join()
            t2.Join()
        Catch e As Exception
            Console.Write(e.ToString())
        Finally
            'Do Nothing
        End Try
    End Sub
    Public Class Account
        Private balanceAmount As Integer
        Public Sub Deposite(ByVal amount As Integer, _
            ByVal message As String)
            Console.Write(message & _
                " Depositing Amount " & amount)
            Console.Write(message & " Checking Previous Balance")
            Monitor.Enter(Me)
            balanceAmount = getBalance()
            Console.Write(message & _
                " Previous Balance in Account " & balanceAmount)
            balanceAmount += amount
            Console.Write(message & _
               " Updating Balance in Account ")
            setBalance(balanceAmount)
            Monitor.Exit(Me)
            Console.Write(message & " Update Balance " & Balance)
            
        End Sub
        Private Function getBalance() As Integer
            Try
                Thread.sleep(1000)
            Catch e As Exception
                Console.Write(e.ToString())
            Finally
                'Do Nothing
            End Try
            Return Balance
        End Function
        
        Private Sub setBalance(ByVal amount As Integer)
            Try
                Thread.sleep(1000)
            Catch e As Exception
                Console.Write(e.ToString())
            Finally
                'Do Nothing
            End Try
            Balance = amount
        End Sub
    End Class
    
    Public Class DepositeBalance
        Private account As Account
        Private amount As Integer
        Private message As String
        
        Public Sub new(ByRef account As Account, _
         ByVal amount As Integer, ByVal message As String)
            MyBase.New()
            Me.account = account
            Me.amount = amount
            Me.message = message
        End Sub
        Public Sub DepositeAmount()
            Account.Deposite(amount, message)
        End Sub
    End Class
End Module