Android Question Immersive mode causes a crash in debug mode

LucaMs

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I "set" immersive mode for the Main; from here I start another Activity and Activity_WindowFocusChanged causes a crash if I start the app in debug mode (see the test project attached).

Copying updated assets files (1)
*** Service (starter) Create ***
** Service (starter) Start **
** Activity (main) Create, isFirst = true **
** Activity (main) Resume **
** Activity (main) Pause, UserClosed = false **
Error occurred on line: 44 (Main)
java.lang.NullPointerException
at b4a.example.main._activity_windowfocuschanged(main.java:427)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:735)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:357)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:260)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:144)
at b4a.example.main.onWindowFocusChanged(main.java:185)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onWindowFocusChanged(PhoneWindow.java:2678)
at android.view.View.dispatchWindowFocusChanged(View.java:8018)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:968)
at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:3289)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:149)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:610)
at dalvik.system.NativeStart.main(Native Method)

Tested only on an Android 4.4.2.
 

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  • ImmveModeTest.zip
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Last edited:

LucaMs

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In the test project attached to the first post, it seems you can solve by changing Sleep(300) to Sleep(100):
B4X:
Sub Activity_WindowFocusChanged(HasFocus As Boolean)
    If HasFocus Then
        Try
            Dim jo As JavaObject = Activity
            Sleep(100)
            jo.RunMethod("setSystemUiVisibility", Array As Object(5894)) '3846 - non-sticky
        Catch
            Log(LastException)
        End Try
    End If
End Sub

but in other projects this change does not solve.
 
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Did you read that from Erel?
he code was updated with a small change.

The Log(LastException) line was commented. The Activity_WindowFocusChanged event can fire after the activity was paused and this line can cause an untrapped exception to be raised.

I tried it with the tip of Erel and it works. :)
 
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LucaMs

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Sometimes the error happens when I write nothing in the Catch part; so I write a Sleep there but... sometimes Sleep(100) is not enough, I have to increase the time, sometimes it is the opposite, I have to decrease this value.

Going by trial:
sometimes it can be solved by "cleaning" the project (CTRL+P), other times stopping the project using the device settings.


Can you post the logs after you commented the relevant line?
** Activity (main) Pause, UserClosed = false **
Error occurred on line: 393 (Main)
java.lang.NullPointerException
at mbnt.MyProjName.it.main._activity_windowfocuschanged(main.java:695)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at anywheresoftware.b4a.shell.Shell.runMethod(Shell.java:735)
at anywheresoftware.b4a.shell.Shell.raiseEventImpl(Shell.java:357)
at anywheresoftware.b4a.shell.Shell.raiseEvent(Shell.java:260)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at anywheresoftware.b4a.ShellBA.raiseEvent2(ShellBA.java:144)
at mbnt.MyProjName.it.main.onWindowFocusChanged(main.java:185)
at com.android.internal.policy.impl.PhoneWindow$DecorView.onWindowFocusChanged(PhoneWindow.java:2678)
at android.view.View.dispatchWindowFocusChanged(View.java:8018)
at android.view.ViewGroup.dispatchWindowFocusChanged(ViewGroup.java:968)
at android.view.ViewRootImpl$ViewRootHandler.handleMessage(ViewRootImpl.java:3289)
at android.os.Handler.dispatchMessage(Handler.java:102)
at android.os.Looper.loop(Looper.java:149)
at android.app.ActivityThread.main(ActivityThread.java:5257)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:515)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:794)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:610)
at dalvik.system.NativeStart.main(Native Method)
 
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LucaMs

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To solve THIS TIME (previous post):

tried both, cleaning and stopping the project, without success.

I added sleep (100) and this solved (then I received the same error in another Activity, resolved in the same way).
 
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LucaMs

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Well, MAYBE I found something "useful" (for Erel :)).

Catch block empty. Start B4A, open the project, run and you get the error.
Change the Sleep command (it does not matter how many ms) inside the Activity_FocusChanged event routine and you no more get the error (in the same "b4a session").

Save the project changed, open and start it again... and again you get the error.
 
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