Cant detect if dark theme is active or not after changing it with AppCompatDelegate

Question

I'm trying to implement an option to let the users specify if they want the app to load the theme based on the system settings (dark or light, i.e., if the device is set to use dark mode or not) but I what also to give the possibility to override the system settings.

I can easily find out how this setting is when launching the app for the first time, using something like the specified in this thread

However these seems to be useless after forcing the theme with:

AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES)

After changing the theme, I can't get the system setting anymore because it will always return "darkmode on", unless I force it again to light theme, but here again it will return "darkmode off" always! :(

Any idea, how to get the system setting?

Thanks in advance,
FF

Ulrick

Answer 1

To detect if "system" is in dark mode or not, you can use getNightMode() method of UiModeManager class.

https://developer.android.com/reference/android/app/UiModeManager#getNightMode()

Like so,

UiModeManager uiModeManager = (UiModeManager) context.getSystemService(Context.UI_MODE_SERVICE);
int mode = uiModeManager.getNightMode();
if (mode == UiModeManager.MODE_NIGHT_YES) {
    // System is in Night mode
} else if (mode == UiModeManager.MODE_NIGHT_NO) {
    // System is in Day mode
}

And if want to know whether "your app" is in Night mode or not:

int mode = getResources().getConfiguration().uiMode & Configuration.UI_MODE_NIGHT_MASK;
    switch (mode) {
        case Configuration.UI_MODE_NIGHT_NO:
            // App is in Day mode
            break;

        case Configuration.UI_MODE_NIGHT_YES:
            // App is in Night mode
            break;

        case Configuration.UI_MODE_NIGHT_UNDEFINED:
            // We don't know what mode we're in, assume notnight
            break;
    }

Scaffolding

Answer 2

After changing the theme, I can't get the system setting anymore because it will always return "darkmode on", unless I force it again to light theme, but here again it will return "darkmode off" always! :( Any idea, how to get the system setting?

In other to change the Theme dynamically you need to use SharedPreferences or Preference for PreferenceScreen. This Github project can help you on how to implement Dark Theme

Morphine

Thanks Kakyire, but I'm already doing that. The issue is if I want to specify to use the system settings after applying the dark theme in the app. It only recognizes the theme already set – Ulrick

Based on your code I figured out what I was doing wrong. Many thanks! – Ulrick

Answer 3

Based on Kakyire's answer I figured out what the problem was.
I was assuming there was only two options to be passed to AppCompatDelegate.setDefaultNightMode, MODE_NIGHT_YES and MODE_NIGHT_NO but the thing is, I needed to pass MODE_NIGHT_FOLLOW_SYSTEM when "use system" is selected.
I hope this might be helpful to someone with the same "dificulty"
Happy coding,
FF

Ulrick