How to view and change the application code on android on a computer?

Question

Android

I want to increase the number of coins in the game

Answer 1

A. First option
1. read the article about jar decompilation
https://habr.com/post/176825/
2. pick jar until the effect is achieved.
B. The second option is a
game cracker for android. (did not try)
https://4pda.ru/forum/index.php?showtopic=190516&st=60