【VISUAL VB NET】Mutex

 Imports System

Imports System.Collections.Generic Imports System.ComponentModel Imports System.Data Imports System.Drawing Imports System.Linq Imports System.Text Imports System.Threading.Tasks Imports System.Windows.Forms ' make sure that using System.Diagnostics; is included Imports System.Diagnostics ' make sure that using System.Security.Principal; is included Imports System.Security.Principal Imports System.Threading Public Class Form1 Public Sub New() MyBase.New() InitializeComponent() If Not IsSingleInstance() Then label1.Text = "There are more instance!" Else label1.Text = "Only one instance!" End If ' Put label in center End Sub ' Declare Mutex object Public mutexx As Mutex Public Function IsSingleInstance() As Boolean Try ' Open existing mutex Mutex.OpenExisting("Mutex") Catch ' Run new instance if app don't exist mutexx = New Mutex(True, "Mutex") ' App start normally Return True End Try ' Return false is app is already opened Return False End Function Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load End Sub End Class