QtActivity, crash at statrup

[mrdebug]

Hi. I can call my method in a my java class correctly. But if I add this line of code
extends org.qtproject.qt5.android.bindings.QtActivity
to the java class my app goes immediatly to crash at startup.
How can I do to resolve?

[mrdebug]

by changing the line to
extends org.qtproject.qt5.android.bindings.QtApplication
now the application starts but when I try to get the NOTIFICATION_SERVICE I obtain a non valid pointer exception.