How to change Android O / Oreo / api 26 app language

Question

I want to change the language of the app and this works fine until API 26.

For api > 25 I put Locale.setDefault(Locale.Category.DISPLAY, mynewlanglocale);

Answer 1

I had the same problem: since Android 8.0+ some parts of my app did't change their language anymore. Updating of both application and activity context helps me. Here is an example of MainActivity function:

private void setApplicationLanguage(String newLanguage) {
    Resources activityRes = getResources();
    Configuration activityConf = activityRes.getConfiguration();
    Locale newLocale = new Locale(newLanguage);
    activityConf.setLocale(newLocale);
    activityRes.updateConfiguration(activityConf, activityRes.getDisplayMetrics());

    Resources applicationRes = getApplicationContext().getResources();
    Configuration applicationConf = applicationRes.getConfiguration();
    applicationConf.setLocale(newLocale);
    applicationRes.updateConfiguration(applicationConf, 
    applicationRes.getDisplayMetrics());
}