Thank you Erel.
I searched, but no quick boot option.
But I thought, that widget would be good for this goal, so I tried it. On an android emulator worked well. Yes, this is the solution! But on the real device the widget example doesn't worked. It looked as if the widgetservice couldn't start. If I delayed the activity.finish, some times the widgetservice could start normally, but not often. So the delaying was unusable.
So I tried a native java widget example and I experienced that it doesn't worked also (except on emulator).
The widget can appear on screen, but don't react any of click.
So no #startatboot, no widget.