Share My Creation B4J single instance

I wanted to limit my app to running as a single instance, in both Windows and Linux.

Several solutions for this single instance problem have been posted, but usually do not include running in Linux.

Erel made a few suggestions in one of his posts. One of these was to use an external file as a marker to indicate that the app is already running.

I took on the task of doing this, and here is my solution.

The "single_instance_test" example attached has many comments which describe how the app works.


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This trick is work if you execute same jar file at the same path, if you run the second jar from different path then the trick does not work.

I have better way to implement single instant of running app, which is by opening specific port at first load, here the code:

Sub Process_Globals
   Private fx As JFX
   Private MainForm As Form
   Private xInstance As UDPSocket '<--- from jNetwork library
End Sub

Sub AppStart (Form1 As Form, Args() As String)
   MainForm = Form1
       xInstance.Initialize("",12340,0) '<--- change the unique port as you want
       Log("Form ready")
       fx.Msgbox(MainForm, "Application already running !","Attention")
   End Try
End Sub