Android Question Prevent running more than one instance of the same APP

[Pedro Caldeira]

Hello guys,
I need to prevent my app to run more than one time.
Is there a way to check if the App is running and prevent from being launched again, by clicking its icon ?

Thanks

 

[Pendrush]

I don't think it is possible to run more then one instance of any app.
There is option on some devices as Xiaomi "second space" that allow two different installation of same app on same device, but you cannot see "other" space from your app, so you cannot prevent two different installation.

 

[artsoft]

I don't think it is possible to run more then one instance of any app.
There is option on some devices as Xiaomi "second space" that allow two different installation of same app on same device, but you cannot see "other" space from your app, so you cannot prevent two different installation.

I know this is an old thread - but please allow my to answer here!

@Pendrush This is not correct completely!

When I start my app with a foreground service (together with a notification icon and message in the message bar), I can go back to my app by clicking the notification.

But when I remove my app from task list and click to the normal app icon which is located on my home screen, I can start a second instance of my app.

And I guess this is exactly what @Pedro Caldeira means.

I also have a XIAOMI Redmi Note 10Pro smartphone. And this fact (the starting of a second instance of my app) is really stupid in the OS!

best regards
ARTsoft

 

[emexes]

I need to prevent my app to run more than one time.
Is there a way to check if the App is running and prevent from being launched again, by clicking its icon ?

I haven't tried it but this post sounds plausible:

https://www.b4x.com/android/forum/threads/b4j-single-instance.101987/#post-644740

(the brilliant solution being to try open an arbitrarily chosen and not normally used server port, because only one process can do so at a time)

 

[edgar_ortiz]

I know this is an old thread - but please allow my to answer here!

@Pendrush This is not correct completely!

When I start my app with a foreground service (together with a notification icon and message in the message bar), I can go back to my app by clicking the notification.

But when I remove my app from task list and click to the normal app icon which is located on my home screen, I can start a second instance of my app.

And I guess this is exactly what @Pedro Caldeira means.

I also have a XIAOMI Redmi Note 10Pro smartphone. And this fact (the starting of a second instance of my app) is really stupid in the OS!

best regards
ARTsoft

Did you find a solution to this problem?

 

[artsoft]

Did you find a solution to this problem?

Unfortunately I have no solution currently :-(

 

[ilan]

But when I remove my app from task list and click to the normal app icon which is located on my home screen, I can start a second instance of my app.

i think this is the point that closes the app.
if you click the icon now you will re-launch the app.
i have never seen an app that has more than 1 instance.

if you press the button to see all your running apps in the background to close them are you seeing your app twice?

i mean this screen:

can you see 2 instance of your app in this screen? if not then your app runs only once!

 

[Serge Bertet]

I don't think it is possible to run more then one instance of any app.

I agree with that.
When I was developping app for Windows using Delphi the solution was to write a key in Windows register at the begining and then remove it at the end.
A launched app reading that key stops immediately when reading this key.
Maybe it is possible to do the same using KVS.

 

[emexes]

When I was developping app for Windows using Delphi the solution was to write a key in Windows register at the begining and then remove it at the end.
A launched app reading that key stops immediately when reading this key.

How did you handle situations where your app didn't finish normally (eg power failure) and thus didn't remove the registry key at the end?

 

[Magma]

@emexes You can have status value... but not the best i think... (especially for an android app)

For example

0 - When App starting
1 - When is in sub....
2 - sub 2...
3 - When app closing

 

[emexes]

@emexes
0 - When App starting
1 - When is in sub....
2 - sub 2...
3 - When app closing

I feel like that would still have the same problem, but... you've got me thinking ? ... maybe including a regularly-updated time in the registry could work.

 

[Serge Bertet]

How did you handle situations where your app didn't finish normally (eg power failure) and thus didn't remove the registry key at the end?

Never happened ... As I remenber Delphi apps have only one entry and exit point. But for sure in case of power failure, I don't know how to deal with that.

 

[Magma]

...but here the problem is an android app... i think if it is an app running at foreground do your job and then getting at home is the exit... is possible... but if runs and at back... seems that will never get a solution... except if you have exit button at app - and only this is the right "EXIT"..

 

[Spavlyuk]

Maybe you can try setting launch mode to singleTask. There are also a few other solutions on SO but not B4A specific: https://stackoverflow.com/questions...droid-application-composed-of-a-single-activi

This happens when Android creates a new instance of the activity instead of reusing the previous one.

You can try to set the task mode to singleTask:

SetApplicationAttribute(android:launchMode,  singleTask)