Android Question CallSubDelayed to open an Activity

[LucaMs]

I was convinced that by calling from a service a routine of an Activity currently not in Foreground, this Activity would be open.

This happen-works only when a different Activity of the app is in Foreground (the app itself is in Foreground); if the app is paused, the call is added to a queue but then it is not executed when the app is bringed in Foreground (except, probably, if the target Activity is already visible).

Is it so?

Has it always been so?

Spoiler: Log - An Activity never opened before.

*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
** Activity (main) Resume **
*** Service (srvservice) Create ***
** Service (srvservice) Start **
** Activity (main) Pause, UserClosed = false **
Calling a routine of act2
sending message to waiting queue of uninitialized activity (routine)
** Activity (main) Resume **

srvservice uses CallSubDelayed to call a routine of act2, which is never executed.

Spoiler: Log - An Activity opened at least once before.

*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
** Activity (main) Resume **
*** Service (srvservice) Create ***
** Service (srvservice) Start **
** Activity (main) Pause, UserClosed = false **
** Activity (act2) Create, isFirst = true **
** Activity (act2) Resume **
** Activity (act2) Pause, UserClosed = false **
** Activity (main) Resume **
** Activity (main) Pause, UserClosed = false **
Calling a routine of act2
sending message to waiting queue (CallSubDelayed - Routine)
** Activity (main) Resume **

srvservice uses CallSubDelayed to call a routine of act2, which is never executed.

 

[Erel]

Check the tutorial: Using CallSubDelayed to interact between activities and services

Is it so?

Yes.

Has it always been so?

Yes.

 

[LucaMs]

Check the tutorial: Using CallSubDelayed to interact between activities and services

I will read it again... maybe for the 5th time

but so, in this case, the queue does nothing (and the call will be removed from it), or am I wrong?

sending message to waiting queue

 

[Erel]

I will read it again... maybe for the 5th time

- If the target module is an activity:
If the application is visible (one of its activities is visible) then the target module will be started if needed and the sub will be called.

but so, in this case, the queue does nothing (and the call will be removed from it), or am I wrong?

It depends on whether the OS kills the process or not. If not then the queues subs will be called when the activity is resumed.

 

[LucaMs]

It depends on whether the OS kills the process or not. If not then the queues subs will be called when the activity is resumed.

but not if a different activity is resumed. If I have the Main in foreground, I "pause" the app, a service calls "sub xxx" of a second activity, when I return to my app, I will see the Main again and the call queued...? Removed, correct?

 

[Erel]

It will wait in queue until the relevant activity is resumed.

 

[LucaMs]

It will wait in queue until the relevant activity is resumed.

losing the useful feature which is to start an activity by calling an its sub with CallSubDelayed.

Ok, thank you, Erel.

 

[Erel]

There is of course a good reason behind it. You should almost never start an activity while your app is in the background. The user doesn't expect it.

 

[LucaMs]

[I hope I do not seem insistent and nagging like... I actually am ]

There is of course a good reason behind it. You should almost never start an activity while your app is in the background. The user doesn't expect it.

I think to cases like this:

1) my app is in foreground, Main activity;
2) I answer to a phone call or anyway I open a different app;
3) meanwhile a service of my app receives a msg to send to a second activity of my app;
4) I return to my app and now I would like that the second activity will be bring on foreground, to show the msg; instead the Main will be displayed and the message will not be displayed (of course I would find the way to save the message and view it later, but this is just an example that has nothing to do with my projects)