How to implement logging in android application?

Question

Java

Hello, I want to sniffer one application, I came to the conclusion that it is possible to modify the application itself:
Add code that would write all outgoing requests and responses to a file.
How can you edit the kernel itself in an application? In order not to touch the code that the developers of this application wrote, or rather how to find it.
Thank you for your attention.

Answer 1

Learn reverse engineering, then decompile the application.
Learn the application code, then study all the commands, then find a way to embed them so that everything compiles back (very time consuming). Then you compile and sign.
PS. It's not worth it in terms of time )
If you just want to see what the application is doing, then reverse is enough. JD-gui + apktool to help you, well, or commercial decompilers, if you have access to them, of course.