I understand that Android is a night mode is to say that it differs if it is day or night, my question is How to get that data and thus be able to change from a clear subject to a dark subject?
Update
The problem that arises after finding how to implement the day / night theme is that when the device rotates it does not just look the same.
Looking at the official documentation can be obtained from UiModeManager .
I've also found that tutorial that implements it from a simple way.
Summing up:
Android Day Night mode, you can differentiate with the suffix -night and in the definition of the theme Theme.AppCompat.DayNight.DarkActionBar the colors of the night interface will be in values-night/colors.xml
To set it to detect it automatically
AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_AUTO);
If you want to force it to be seen in Night mode
AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
If you want to see it in the default mode it means day mode.
AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
Downloadable tutorial example: DayNightThemeExample