I'm trying to develop an Android app.

I'm going to develop APK with Android studio program now. It's my first time using Java and using all the apps..."T" I even made a screen change by pressing the start button from main to sub.

Display user's storage space and RAM usage ratio in the Play Store like the 'Clean Master' app

I want to be able to download or run a coded program by pressing a specific button.

I would like to know if it is possible to write only Java or if C or Python is also possible.

If you look at these apps, there is a part that requests access to the device, and it is said to add a permission, can you explain it in detail?