CODEWITHSUNDEEP
android
Niklas Dada
Niklas Dada

Reputation: 401

AndroidX FragmentActivity incompatible with Dark/Night Mode Changes

I searched around for a while and had to "learn it the hard way":

FragmentActivity from androidx.fragment.app.FragmentActivity does NOT work together with the documented way to change themes.

So for example: You switch from day-theme to night-theme via AppCompatDelegate.setDefaultNightMode() in the onCreate() of you App class (a class which extends the Application class) because the configuration is not persistent after closing/opening the app and to make sure the configuration change (which is triggered by setDefaultNightMode()) is done before any activities are created. So far so good: I.E. An AppCompatActivity will be created using the preferred theme. BUT if you launch a FragmentActivity this activity will not use the resources provided for night mode.

I used

    void checkNightModeConfiguration() {
        int currentNightMode = getResources().getConfiguration().uiMode
                & Configuration.UI_MODE_NIGHT_MASK;
        switch (currentNightMode) {
            case Configuration.UI_MODE_NIGHT_NO:
                Log.i(TAG, "night mode flag NOT set");
                break;
            case Configuration.UI_MODE_NIGHT_YES:
                Log.i(TAG, "night mode flag set");
                break;
            case Configuration.UI_MODE_NIGHT_UNDEFINED:
                Log.i(TAG, "night mode flag unknown");
                break;
        }
    }

to check when the activity reads out the configuration. For AppCompatActivity this already happened in the beginning of onCreate(). For FragmentActivity this happens a while later (maybe someone could clarify at which point this happens?), definitely after the layout is infalted and therefore the layout is never inflated with the night resources.

For me the easiest solution was to use AppCompatActivity instead because I do not need the backwards compatibility for nested fragments and do not support API Level < 17 (see this post).

Hope this safes time for some of you out there.

Sources

DayNight — Adding a dark theme to your app

Activity, AppCompatActivity, FragmentActivity, and ActionBarActivity: When to Use Which?

Developing Themes with Style (Android Dev Summit '19)

Upvotes: 0

Views: 1494

Answers (1)

ianhanniballake
ianhanniballake

Reputation: 200120

FragmentActivity, being part of the Fragment library and having no dependency on AppCompat (in fact, AppCompat depends on Fragment) is totally unaware of AppCompatDelegate and any night mode you set on that object.

You should always use AppCompatActivity if you want your activity to be aware of AppCompatDelegate and any of the night mode fixes that are specific to AppCompat.

Upvotes: 2

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