Android Question How to Keep public variable when device get into deep sleep

[karyadi]

Hi All,

i have a question,
How to Keep public variable when device get into deep sleep?
because every time my device get into deep sleep, all my variable become null.

thanks

 

[klaus]

because every time my device get into deep sleep, all my variable become null.

How and where do you declare them ?

 

[KMatle]

Save them to a file (Activity_Pause) or at your need. Reload it (Activity_Resume) or at your need.

 

[marcick]

because every time my device get into deep sleep, all my variable become null.

How is it possible ???

 

[FrankBerra]

I think Starter Service can help you keeping variables in memory:
https://www.b4x.com/android/forum/threads/starter-service-consistent-single-entry-point.57599/

 

[karyadi]

How and where do you declare them ?

Hi Klaus, i declare on my Main activity

Sub Process_Globals.

I think Starter Service can help you keeping variables in memory:

https://www.b4x.com/android/forum/threads/starter-service-consistent-single-entry-point.57599/

i already try using starter service to keep my variable, but it's doesn't work.

Save them to a file (Activity_Pause) or at your need. Reload it (Activity_Resume) or at your need.

Yes your advice can be use, or maybe there is more simple way to keep thje variable?

 

[DonManfred]

simple way to keep thje variable?

Yes. The starter service.

If it does not work for you then you should upload your project showing the problem.

 

[marcick]

I can't believe it .....
Is that true ?

 

[DonManfred]

I can't believe it .....
Is that true ?

What do you cant believe?

 

[marcick]

That values of global variables are lost and the app resume without them.
That would mean I did huge mistakes in programming and I should put hands on all my apps if really can happen.

 

[DonManfred]

That values of global variables are lost and the app resume without them.

It can happen if you use app-killer while your app is in the background. Or if Android decided to kill your app (in background) due to low resources.

 

[klaus]

One solution is a file as already sugested.
You may also have a look ar the KeyValueStore Class.

 

[marcick]

If the app is killed, then when restarted you have all the reinitialuzation needed.
What I can't believe is the app is just resumed with lost variables.

 

[marcick]

Maybe I didn't get the question but I want to be sure.
Look to this simple project

Sub Process_Globals
    Dim test1 As String
End Sub

Sub Globals
    Dim test2 As String
End Sub

Sub Activity_Create(FirstTime As Boolean)
    test1="hello"
    test2="hello"
End Sub

Sub Activity_Resume
    Log(test1)
    Log(test2)
End Sub

Can I be sure that each time the app is started or resumed the variables test1 and test2 contain "hello" ?
Does it exists any situation the app is resumed without those variables ?

 

[Erel]

There are several mistakes in this code:
1. Don't use Dim in Process_Globals. Use Private or Public instead.
As a general rule public process global variables should be declared and set in the Starter service (Service_Create).

2. Non-UI objects should be declared in Process_Globals instead of Globals.
3. Process_Global variables should only be set when FirstTime is true (in this case it doesn't really matter).

 

[marcick]

Ok.
Talking about apps written and published before the introduction of the starter_service in B4A, I put again the question about this code:

Sub Process_Globals
    Public test1 As String
End Sub

Sub Globals
    Public test2 As String
End Sub

Sub Activity_Create(FirstTime As Boolean)
   If FirstTime=true then
       test1="hello"
       test2="hello"
   End If
End Sub

Sub Activity_Resume
    Log(test1)
    Log(test2)
End Sub

Can I be sure that each time the app is started or resumed the variables test1 and test2 contain "hello" ?
Does it exists any situation the app is resumed without those variables ?

 

[Erel]

Almost. If test2 is a global variable then it must always be set in Activity_Create. Not just when FirstTime is true.

See this quiz: https://www.b4x.com/android/forum/t...-process-activities-life-cycle.37899/#content

 

[marcick]

So:

Sub Process_Globals
    Public test1 As String
End Sub

Sub Globals
    Public test2 As String
End Sub

Sub Activity_Create(FirstTime As Boolean)
   If FirstTime=true then
       test1="hello"
   End If
   test2="hello"
End Sub

Sub Activity_Resume
    Log(test1)
    Log(test2)
End Sub

If this code is correct, is it the answer to karyadi (first post) ?

 

[Erel]

I'm afraid no.
1. Global variables cannot be public (though this is not a real issue).
2. Process global variables should be declared and set in the starter service. This is a real issue.

Assuming that Main.test1 is accessed from Activity2 then at some point Activity2 will start before Main and the variable will not be set.

 

[marcick]

Need to print this topic, append to the wall and read it every day. Much confusion in my head.
But again I want to put the question in a simpler way (same code as above):
Suppose the app start normally from Activity1 and test1 and test2 are both set to "hello".
These two variables, are kept forever (until the app is closed or killed by OS of course) or can happen the app RESUME with NULL in them ?