Where can I get examples of tasks for a beginner Android developer to improve my level?

Question

Java

Good afternoon! I am a beginner Android developer. It is interesting to work with more or less real projects for training. Since some basic things are already clear and obvious, we need examples of applications in which it would be well represented:
a) the architecture of a complex mobile application (authorization, working with the back-end server, proper encryption, etc)
c) examples of a good (competent) user interface .
Also interesting are examples of applications whose level corresponds to the Android Developer level of the employer.
I understand that everything sounds something like "what is the average temperature in the hospital", nevertheless.
I would really appreciate specific links!
Thanks a lot!

Answer 1

https://github.com/ in the search you make a request for the word android, this is your average temperature

Answer 2

for the Android Developer level at the employer, it is better to deal with Java Core in detail.