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

After use all solution in all sources finally i found my issue. That makes me angry for 2 days.

Everyone knows that in Android Oreo (API 26) we must use createConfigurationContext, But My problem is using Country name with local.

Replace

en_US with en

ar_AE with ar

fa_IR with fa

And my problem solved.

Hope to help someone