Android Question Crash with MsgboxAsync

Creideiki · Jan 28, 2020

Hi there,

I try to convert the Msgboxes to MsgboxAsync. Since there are some MsgBoxes one after the other, I try to de-parallelize them with Wait For.
Now I got a crash:

Code:

lizenzclass$ResumableSub_leseDateiresume (java line: 213)
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.lang.ref.WeakReference.get()' on a null object reference
    at anywheresoftware.b4a.keywords.Common.Msgbox2Async(Common.java:488)
    at anywheresoftware.b4a.keywords.Common.MsgboxAsync(Common.java:466)
    at de.xxx.yyy.lizenzclass$ResumableSub_leseDatei.resume(lizenzclass.java:213)
    at de.xxx.yyy.lizenzclass._lesedatei(lizenzclass.java:125)
    at de.xxx.yyy.main$ResumableSub_findeLizenz.resume(main.java:2797)
    at de.xxx.yyy.main._findelizenz(main.java:2633)
    at de.xxx.yyy.main$ResumableSub_pruefeLizenz.resume(main.java:3220)
    at anywheresoftware.b4a.BA.checkAndRunWaitForEvent(BA.java:250)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:190)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:176)
    at anywheresoftware.b4a.keywords.Common$1.onClick(Common.java:492)
    at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:169)
    at android.os.Handler.dispatchMessage(Handler.java:110)
    at android.os.Looper.loop(Looper.java:203)
    at android.app.ActivityThread.main(ActivityThread.java:6251)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
java.lang.NullPointerException: Attempt to invoke virtual method 'java.lang.Object java.lang.ref.WeakReference.get()' on a null object reference

The code is quite complex.
The original call is in Main.Activity_Create. It calls a resumable sub (well, since I need Wait For, many subs have to be resumable) called pruefeLizenz. That one calls leseDatei in the Class LizenzClass. The instance of this class is declared in Main.Process_Globals and initialized in Starter.
In this sub, the App crashes while calling an simple MsgboxAsync.

I tried to create a litte App, which mimic the behaviour of the original app to show the crash; but this app works as expected.

I have no idea what could happen there. I am quite shure the logical flow is correct; I think it has something to do with the resumable sub / async thing and perhaps a problem with the right context.
Has anybody an idea what's going wrong?

Thank you.

Computersmith64 · Jan 28, 2020

Are you using the Sender Filter on your message boxes? This thread might help you.

- Colin.

Creideiki · Jan 29, 2020

Thanks for your Answer.
To use the Sender Filter I need an object to filter. Msgbox2Async returns an object, but MsgboxAsync doesn't. So I can't filter here.

Creideiki · Jan 29, 2020

I rewrote the crashing part a bit.
I concentrated the Msgboxes of leseDatei in a sub named showLeseErgebnis with one MsgboxAsync. Same error.
I then replaced the MsgboxAsync by a Msgbox2Async and used the sender filter. Same error.
I then replaced the MsgboxAsync by a simple Msgbox and got the following crash:

Code:

lizenzclass$ResumableSub_showLeseErgebnisresume (java line: 412)
android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application
    at android.view.ViewRootImpl.setView(ViewRootImpl.java:800)
    at android.view.WindowManagerGlobal.addView(WindowManagerGlobal.java:351)
    at android.view.WindowManagerImpl.addView(WindowManagerImpl.java:93)
    at android.app.Dialog.show(Dialog.java:322)
    at anywheresoftware.b4a.Msgbox.msgbox(Msgbox.java:169)
    at anywheresoftware.b4a.keywords.Common.Msgbox2(Common.java:454)
    at anywheresoftware.b4a.keywords.Common.Msgbox(Common.java:433)
    at de.okabrechnungssysteme.HKZaehlerB4A.lizenzclass$ResumableSub_showLeseErgebnis.resume(lizenzclass.java:412)
    at de.okabrechnungssysteme.HKZaehlerB4A.lizenzclass._showleseergebnis(lizenzclass.java:295)
    at de.okabrechnungssysteme.HKZaehlerB4A.main$ResumableSub_findeLizenz.resume(main.java:2799)
    at de.okabrechnungssysteme.HKZaehlerB4A.main._findelizenz(main.java:2633)
    at de.okabrechnungssysteme.HKZaehlerB4A.main$ResumableSub_pruefeLizenz.resume(main.java:3222)
    at anywheresoftware.b4a.BA.checkAndRunWaitForEvent(BA.java:250)
    at anywheresoftware.b4a.BA.raiseEvent2(BA.java:190)
    at anywheresoftware.b4a.BA.raiseEvent(BA.java:176)
    at anywheresoftware.b4a.keywords.Common$1.onClick(Common.java:492)
    at com.android.internal.app.AlertController$ButtonHandler.handleMessage(AlertController.java:169)
    at android.os.Handler.dispatchMessage(Handler.java:110)
    at android.os.Looper.loop(Looper.java:203)
    at android.app.ActivityThread.main(ActivityThread.java:6251)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1063)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:924)
android.view.WindowManager$BadTokenException: Unable to add window -- token null is not for an application

Creideiki · Jan 29, 2020

Next try: I moved the sub to Main. That works.

I have to refactor the whole App to replace MsgBox with MsgboxAsync. When I have to move each and any MsgBox out of the Class modules, that will be an desaster. I know it's better to du UI in the Activities, but there are many places it would get very expensive to move any UI out of the Classes.

For clarity, here the excerpt of the relevant subs:

Code:

Private Sub findeLizenz As ResumableSub
    Dim fd As FileDialog
    '[...]
    If fd.Show("Lizenz-Datei suchen","OK","Abbruch","",Null) <> DialogResponse.POSITIVE Then
        MsgboxAsync("Benutzerabbruch, kein Lizenz übernommen", "Lizenz")
        Wait For MsgBox_Result (Result As Int)
        Return False
    End If
    '[...]
    Wait For (Lizenz.showLeseErgebnis(stat)) Complete (Result As Int)
    Return stat = Lizenz.DATEISTATUS_OK
End Sub

Code:

Public Sub showLeseErgebnis(status As Int) As ResumableSub
    Dim txt As String
    Select status
        Case Lizenz.DATEISTATUS_OK:            txt = "Lizenz wurde gespeichert."
        Case Lizenz.DATEISTATUS_WRONGPROG:    txt = "Die Lizenz-Datei gehört nicht zu " & sProgLizenzName
        Case Lizenz.DATEISTATUS_NOCHECK:    txt = "MAC Adresse und IMEI sind nicht verfügbar, Lizenz kann nicht geprüft werden!" & CRLF & _
            "Das WLAN muss zur Prüfung eingeschaltet sein!"
        Case Lizenz.DATEISTATUS_WRONGMAC:    txt = "Die Lizenz-Datei gehört nicht zu diesem Gerät mit MAC: " & ALLG.GetDeviceMAC
        Case Lizenz.DATEISTATUS_WRONGIMEI:    txt = "Die Lizenz-Datei gehört nicht zu diesem Gerät mit IMEI: " & ALLG.GetDeviceId
        Case Lizenz.DATEISTATUS_WRONGKEY:    txt = "Der Lizenz-Key ist falsch, bitte an Support wenden."
        Case Else:                            txt = "Interner Fehler: Status " & status
    End Select
    Dim sf As Object = Msgbox2Async(txt, "Lizenzprüfung", "OK", "", "", LoadBitmap(File.DirAssets, "btn_info.png"), False)
    Wait For (sf) MsgBox_Result (Result As Int)
    Return 0
End Sub

Erel · Jan 29, 2020

Not sure what exactly you are implementing however you can only show dialogs from a class that was initialized in an activity.

Creideiki · Jan 29, 2020

So since the instance is initialized in the Starter service I can't use dialogs, right?

DonManfred · Jan 29, 2020

Creideiki said:
So since the instance is initialized in the Starter service I can't use dialogs, right?

Yes

Creideiki · Jan 29, 2020

Well... I think I hat a similar problem already... but I didn't remember...

I should've created the module as code module, not as class. But I thought it should be accessible from other parts, too... well, that's not necessary. So now it's created and initialized locally and anything works as a charm.

Thanks to Erel and DonManfred.

Erel · Jan 29, 2020

Creideiki said:
I should've created the module as code module, not as class.

This will not help.
You cannot show a dialog from a service context.

Creideiki · Feb 3, 2020

Erel said:
This will not help.
You cannot show a dialog from a service context.

It's called from the Main Activity. So that's no problem.

Is it possible to convert a class module to a code module?

Erel · Feb 3, 2020

Changing to code module will not help and is a mistake.

You will need to copy the code to the new module.

Creideiki · Feb 3, 2020

Erel said:
Changing to code module will not help and is a mistake.

Why? I realized I don't need the features of an Object, but only want to have the relevant code in one place.

You will need to copy the code to the new module.

ok. Thanks.

Erel · Feb 3, 2020

Classes are superior over code modules.
Code modules cannot handle events and therefore cannot have resumable subs.
The correct solution is to understand what causes this crash.

Creideiki · Feb 3, 2020

Erel said:
Code modules cannot handle events and therefore cannot have resumable subs.

Oh, ok... that's a showstopper indeed. I thought code modules would work as if the code was in the calling module... but since we have to replace the Msgboxes by the Async variants we have to use resumable subs.

The correct solution is to understand what causes this crash.

-> Object was initialized in Starter service instead of the Activity => solved ??

Android Question Crash with MsgboxAsync

Creideiki

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Computersmith64

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Creideiki

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Creideiki

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Creideiki

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Erel

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Creideiki

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DonManfred

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Creideiki

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Erel

B4X founder

Creideiki

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Erel

B4X founder

Creideiki

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Erel

B4X founder

Creideiki

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