Android Question Regarding not being able to use MsgBox from Starter

[Sandman]

We all know that we can't show UI things from Starter (or any services really), like MsgBox etc. (Toasts are an exception for some reason, but for this thread I'll ignore them.)

Let's say I have a class in Starter. Then that class won't be able to use MsgBox etc. And if that class has a class in it, that in turn has a class in it, then that can't show MsgBox etc. You know, it's not possible, because they all inherit the Starter context.


So my question is this:

Is there a way for a sub to detect if it's in a Starter (or other service) context and thus cannot show MsgBox etc?

 

[LucaMs]

Is there a way for a sub to detect if it's in a Starter (or other service) context and thus cannot show MsgBox etc?

I don't know if that's possible (perhaps using Reflector) but... at that point what would your class do if it could realize it couldn't display the message, wouldn't it?

I would avoid using the Starter and other services as well; indeed, I just avoid doing it.

 

[Sandman]

I would avoid using the Starter and other services as well; indeed, I just avoid doing it.

It's not really the topic of the thread, but I'll bite. In my case my app can wake up because a geofence event happened so the OS start one of my services. At that point I can only count on two things being alive: The service started, and Starter.

So in my case it makes sense to put important classes Starter so they are always available.

Opinions on this are welcome.

what would your class do if it could realize it couldn't display the message

I don't know really, I'm just trying to figure out if it's even possible at the moment.

 

[agraham]

Is there a way for a sub to detect if it's in a Starter (or other service) context and thus cannot show MsgBox etc?

Easiest way is to pass a flag as a parameter to the Sub as the programmer will know if it is being called in a service or not.

 

[LucaMs]

It's not really the topic of the thread, but I'll bite. In my case my app can wake up because a geofence event happened so the OS start one of my services. At that point I can only count on two things being alive: The service started, and Starter.

So in my case it makes sense to put important classes Starter so they are always available.

Opinions on this are welcome.



I don't know really, I'm just trying to figure out if it's even possible at the moment.

1. use the B4XPages, which very often solve this type of problem.
2. put the instances of the classes in the B4XMainPage or, if you don't want to use them, in the Activity Main (public variables) and in the Starter put only the calls to the methods of those objects.

 

[Sandman]

Easiest way is to pass a flag as a parameter to the Sub as the programmer will know if it is being called in a service or not.

Yeah, sure, but is there a way to not have to do it like that and instead do some magic with JavaObjects or something like that?

 

[Sandman]

use the B4XPages, which very often solve this type of problem

How on earth would B4XPages solve this? Like I wrote, when the OS wakes my service, only that service and Starter is alive. At no point during that is B4XPages initialized.

 

[LucaMs]

How on earth would B4XPages solve this? Like I wrote, when the OS wakes my service, only that service and Starter is alive. At no point during that is B4XPages initialized.

Yes, but then (after) B4XPages can help. Anyway, the second part of my post is more useful (I think )

 

[LucaMs]

Yes, but then (after) B4XPages can help. Anyway, the second part of my post is more useful (I think )

I mean: put only the bare minimum in the Starter.

 

[Sandman]

Anyway, the second part of my post is more useful (I think )

I suppose you mean the part below?

in the Activity Main

I have to ask, I can't remember the details about Main at the moment, but does Main always exist, as Starter does? Even when an app is launched like I've described, as the OS starts a service?

 

[Sandman]

Also relevant, in this thread...

Starter Service - Consistent & Single Entry Point

One of the challenges that developers of any non-small Android app need to deal with, is the multiple possible entry points. During development in almost all cases the application will start from the Main activity. Many programs start with code similar to: Sub Activity_Create (FirstTime As...

www.b4x.com

...Erel says
”the Starter service is the best place to initialize all the application-wide resources”

 

[LucaMs]

I suppose you mean the part below?

2 - put the instances of the classes in the B4XMainPage or, if you don't want to use them, in the Activity Main (public variables) and in the Starter put only the calls to the methods of those objects.

I mean: put only the bare minimum in the Starter.

I have to ask, I can't remember the details about Main at the moment, but does Main always exist, as Starter does? Even when an app is launched like I've described, as the OS starts a service?

Yes, it exists immediately after starting the Starter. Using B4XPages, it will never pause, this is a great opportunity.

 

[LucaMs]

Also relevant, in this thread...

Starter Service - Consistent & Single Entry Point

One of the challenges that developers of any non-small Android app need to deal with, is the multiple possible entry points. During development in almost all cases the application will start from the Main activity. Many programs start with code similar to: Sub Activity_Create (FirstTime As...

www.b4x.com

...Erel says
”the Starter service is the best place to initialize all the application-wide resources”

Yes but that only applies to B4A projects, of course. I prefer to initialize everything in the B4XMainPage, so if at a later time I want to create the iOS app, most of the work will be ready.

 

[William Lancee]

This may be too obvious, but I tested this and it works. When called from Main it shows message if called from Starter it does not.
In you class wrap the msg function in a try block.

Public Sub displayMsg(s As String)
    Try
        xui.MsgboxAsync(s, "Test Title")
    Catch
        Log(LastException)
    End Try
End Sub

 

[Sandman]

This may be too obvious

Not at all, that's a clever solution! But with a slight downside: If it works, it does display a MsgBox. Can we find a way to passively detect it?

 

[LucaMs]

Not at all, that's a clever solution! But with a slight downside: If it works, it does display a MsgBox. Can we find a way to passively detect it?

 

[William Lancee]

Now I am confused too. If it works it is called from an Activity context, if not then it is called from a Service.
I suppose that it isn't a msgbox per se you want to detect, just whether or not a sub is called from an Activity context or not.

Are there non-msg functions that depend on the Activity context? Ones that don't have a UI result? If so put one of these in the Try block.
There may be. Right now I can't think of any.

 

[William Lancee]

I found something https://www.b4x.com/android/forum/t...-module-compile-to-library.120080/post-750782

    Private ctxt As JavaObject
    Log("***" & GetType(ctxt.InitializeContext))

    'Log for Starter call: ***android.app.Application
    'Log for Activity call: ***b4a.example.main

 

[Sandman]

I suppose that it isn't a msgbox per se you want to detect, just whether or not a sub is called from an Activity context or not.

Yep, that's correct, it's possible to do it from that direction too.

 

[Sandman]

I found something https://www.b4x.com/android/forum/t...-module-compile-to-library.120080/post-750782

    Private ctxt As JavaObject
    Log("***" & GetType(ctxt.InitializeContext))

    'Log for Starter call: ***android.app.Application
    'Log for Activity call: ***b4a.example.main

Oh, that's interesting. That could very well be it. I have to do some tests tomorrow. Thanks!