How do you start to edit someone else's "shit code"?

Question

Android

Such a mess in the code that I don’t even know which side to start from ...)

Answer 1

If the search for an error / bug in the code takes longer than if you wrote your own clean code, feel free to huawei delete it.

Answer 2

start with meditation, this will help you understand the previous developer and the reason that prompted him to write what he wrote.

Answer 3

Go to church....
Seriously, take a look at the architecture. On the basis of which the person wrote the previous version. Further, depending on the task.