如何在Android Studio上永久更改语言？

Question

I created an Android app with Android Studio that can change language settings while executing it from the top menu button . Everything works, but whenever I close the app or I rotate the screen the language keeps getting reset to the system one. How to make changes inside the app permanent ? (Note that inside AndroidManifest.xml I have the following line android:configChanges="locale" and deleting it doesn't solve the issue.) I'm using the following code inside my MainActivity.java :

 public void changeLanguage (String toLoad) {
        Locale locale = new Locale(toLoad);
        Locale.setDefault(locale);
        Configuration config = new Configuration();
        config.locale= locale;
        getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());
        Intent intent = new Intent(MainActivity.this, MainActivity.class);
        intent.setFlags(Intent.FLAG_ACTIVITY_CLEAR_TOP);
        startActivity(intent);
    }

    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        String languageToLoad;
        switch (item.getItemId()) {
            case R.id.english_menu:  
                languageToLoad = "en";             
                changeLanguage(languageToLoad);
                return true;
            case R.id.italian_menu:              
                languageToLoad = "it";
                changeLanguage(languageToLoad);
                return true;
            case R.id.french_menu:              
                languageToLoad = "fr";
                changeLanguage(languageToLoad);
                return true;               
            default:
                return super.onOptionsItemSelected(item);
        }
    }

Answer 1

Save user preference to shared preferences .

/******* Create SharedPreferences *******/

    SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", MODE_PRIVATE); 
    Editor editor = pref.edit();


/**************** Storing data as KEY/VALUE pair *******************/


    editor.putString("lang_code", "en");  // Saving string

    // Save the changes in SharedPreferences
    editor.commit(); // commit changes

create application class and oncreate method of this class set your application local

public class BaseJuiceApplication extends Application{

    @Override
    public void onCreate() {
        super.onCreate();
    SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", MODE_PRIVATE);

        Locale locale = new Locale(pref.getString("lang_code","en"));
        Locale.setDefault(locale);
         Configuration conf = getBaseContext().getResources().getConfiguration(); 
        config.locale= locale;
        getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());


    }

}