Cannot switch between modes in DayNight theme dynamically

Question

I implemented the DayNight theme in my app and added a setting to switch between day and night mode, but I'm not able to switch between modes dynamically without a restart.

If I use setDefaultNightMode() after the setting has been changed, the settings activity doesn't change mode, but the activities in the backstack do. If I additionally use setLocalNightMode() the settings activity gets recreated and changes its mode, but now the activities in the backstack don't. I could not find a way to accomplish both. Is there a way to do this?

score 6 · Answer 1 · answered May 23 '17 at 08:19

Here is the implementation in the MainActivity.java module of the CheeseSquare repo located here:

private void setNightMode(@AppCompatDelegate.NightMode int nightMode) {
    AppCompatDelegate.setDefaultNightMode(nightMode);

    if (Build.VERSION.SDK_INT >= 11) {
        recreate();
    }
}

Here is the description of recreate() as of V25. I can't seem to find other documentation for this call - note that it was added at V11.

/* Cause this Activity to be recreated with a new instance.  This results
 * in essentially the same flow as when the Activity is created due to
 * a configuration change -- the current instance will go through its
 * lifecycle to {@link #onDestroy} and a new instance then created after it.
 */

It works if you do this in the MainActivity, but if you do this in another activity with the MainActivity in the backstack the problem remains. — Özgür, May 24 '17 at 20:16
What works for me is to "turn off" the backstack by turning off history in the manifest file. Add `android:noHistory="true"` to your activities as described here: https://stackoverflow.com/questions/5794506/android-clear-the-back-stack/6512788#6512788 — Jim Andreas, May 25 '17 at 05:48

Artem Mostyaev · Answer 2 · 2018-05-18T12:48:00.233

I got it to work, here is my code and screen record. Activities in the backstack are also changing their themes.

findPreference(getString(R.string.pref_key_night_mode)).setOnPreferenceChangeListener(new OnPreferenceChangeListener() {

        @Override
        public boolean onPreferenceChange(Preference preference, Object newValue) {
            if ((Boolean) newValue) {
                AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_YES);
                getDelegate().setLocalNightMode(AppCompatDelegate.MODE_NIGHT_YES);
            } else {
                AppCompatDelegate.setDefaultNightMode(AppCompatDelegate.MODE_NIGHT_NO);
                getDelegate().setLocalNightMode(AppCompatDelegate.MODE_NIGHT_NO);
            }
            getDelegate().applyDayNight();
            recreate();
            return true;
        }

    });

Update

The solution above worked for Android 4.4 well, but preserved previous DayNight state in backstack on Android 7.1.

I've added manual check for night mode setting change in onResume:

@Override
protected void onResume() {
    super.onResume();
    if (mApplyNightMode) {
        mApplyNightMode = false;
        getDelegate().setLocalNightMode(PeshkaPreferences.getNightModeEnabled(this) ? AppCompatDelegate.MODE_NIGHT_YES : AppCompatDelegate.MODE_NIGHT_NO);
        getDelegate().applyDayNight();
        recreate();
    }
}

and added OnSharedPreferencesChangeListener:

protected OnSharedPreferenceChangeListener mPreferencesListener = new OnSharedPreferenceChangeListener() {

    @Override
    public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
        if (key.equals(getString(R.string.pref_key_night_mode))) {
            mApplyNightMode = true;
        }
    }
};

May be you should update your answer based on the current updates — Abraham Mathew, May 13 '20 at 04:27

Cannot switch between modes in DayNight theme dynamically

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