Resources and layout direction rendered incorrectly only on Android 8.0 and above

The updateConfiguration() method was deprecated

Now we need to use createConfigurationContext()

I have managed this way

create a new class ContextWrapper

import android.content.Context;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.os.Build;
import android.os.LocaleList;

import java.util.Locale;

public class ContextWrapper extends android.content.ContextWrapper {

    public ContextWrapper(Context base) {
        super(base);
    }

    public static ContextWrapper wrap(Context context, Locale newLocale) {

        Resources res = context.getResources();
        Configuration configuration = res.getConfiguration();

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            configuration.setLocale(newLocale);

            LocaleList localeList = new LocaleList(newLocale);
            LocaleList.setDefault(localeList);
            configuration.setLocales(localeList);

            context = context.createConfigurationContext(configuration);

        } else if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
            configuration.setLocale(newLocale);
            context = context.createConfigurationContext(configuration);

        } else {
            configuration.locale = newLocale;
            res.updateConfiguration(configuration, res.getDisplayMetrics());
        }

        return new ContextWrapper(context);
    }}

create a new class of BaseActivity

import android.content.Context;

import android.support.v7.app.AppCompatActivity;

import java.util.Locale;

/**
 * Created by nilesh on 20/3/18.
 */

public class BaseActivity extends AppCompatActivity {

    @Override
    protected void attachBaseContext(Context newBase) {

        Locale newLocale;

        String lang = new PrefManager(newBase).getLanguage();

        if (lang.equals("zh_CN")) {
            newLocale = new Locale("zh");
        } else {
            newLocale = new Locale(lang);
        }


        Context context = ContextWrapper.wrap(newBase, newLocale);
        super.attachBaseContext(context);
    }
}

Create a PrefManager class to store locale

import android.content.Context;
import android.content.SharedPreferences;

public class PrefManager {

    private SharedPreferences.Editor editor;
    private Context mContext;
    private SharedPreferences prefs;
    private final String LANGUAGE = "language";
    private final String PREF = "user_data";

    public PrefManager(Context mContext) {
        this.mContext = mContext;
    }

    public String getLanguage() {
        this.prefs = this.mContext.getSharedPreferences(PREF, 0);
        return this.prefs.getString(LANGUAGE, "en_US");
    }

    public void setLanguage(String language) {
        this.editor = this.mContext.getSharedPreferences(PREF, 0).edit();
        this.editor.putString(LANGUAGE, language);
        this.editor.apply();
    }

}

Now you need to extends your BaseActivity in your all activity like

public class OrdersActivity extends BaseActivity

Now when your need to change Locale just update the value in PrefManager and restart your activity

    PrefManager prefManager= new PrefManager(this);
    prefManager.setLanguage("zh_CN");
    //  restart your activity

NOTE

You can download source code from github repo

The method Resources#updateConfiguration (Configuration config, DisplayMetrics metrics) is deprecated in API level 25.

The doc suggests to use Context#createConfigurationContext (Configuration overrideConfiguration)

You can simply make a base activity which is a common parent of all the activities as shown below.

public class BaseActivity
        extends AppCompatActivity {

    private static final String LANGUAGE_CODE_ENGLISH = "en";
    private static final String LANGUAGE_CODE_ARABIC = "ar";

    @Override
    protected void attachBaseContext(Context newBase) {
        super.attachBaseContext(getLanguageAwareContext(newBase));
    }

    private static Context getLanguageAwareContext(Context context) {
        Configuration configuration = context.getResources().getConfiguration();
        configuration.setLocale(new Locale(getLanguageCode()));
        return context.createConfigurationContext(configuration);
    }

    // Rewrite this method according to your needs
    private static String getLanguageCode() {
        return LANGUAGE_CODE_ARABIC;
    }
}

Notes

• getLanguageCode() should return language code. Typically the language code or any other data representing it is stored in preferences.
• To change languages dynamically, recreate activity after setting appropriate language code into preferences.
• Use activity context rather than application context to access any locale specific resources. In other words, use this or ActivityName.this from activities and getActivity() from fragments instead of getApplicationContext().

The complete solution to this problem consists of three steps:

STEP 1:

In the onCreate() of your BaseActivity (or all your Activitys), set the Locale as follows:

@Override
protected void onCreate(Bundle savedInstanceState) {

    // set the Locale the very first thing
    Utils.setLocale(Utils.getSavedLocale());
    requestWindowFeature(Window.FEATURE_NO_TITLE);
    super.onCreate(savedInstanceState);

    ......
    ......

}

where getSavedLocale() is the Locale corresponding to the current region (this will be specific for your project ... ).

And the method Utils.setLocale(...) is defined as follows:

public static void setLocale(Locale locale){
    Context context = MyApplication.getInstance();
    Resources resources = context.getResources();
    Configuration configuration = resources.getConfiguration();
    Locale.setDefault(locale);
    configuration.setLocale(locale);
    configuration.setLayoutDirection(locale);

    // updateConfiguration(...) is deprecated in N
    if (Build.VERSION.SDK_INT >= 25) {
        context = context.getApplicationContext().createConfigurationContext(configuration);
        context = context.createConfigurationContext(configuration);
    }

    context.getResources().updateConfiguration(configuration,
            resources.getDisplayMetrics());
}

This sets the correct Locale in every Activity. This is enough for apps supporting API level 25. For API level 26 & above, STEP 2 and STEP 3 are also required.

STEP 2:

Override the following method in your BaseActivity:

@Override
protected void attachBaseContext(Context newBase) {
    newBase = Utils.getLanguageAwareContext(newBase);
    super.attachBaseContext(newBase);
}

where the function getLanguageAwareContext(...) is defined as follows:

public static Context getLanguageAwareContext(Context context){
    Configuration configuration = context.getResources().getConfiguration();
    Locale locale = getIntendedLocale();
    configuration.setLocale(locale);
    configuration.setLayoutDirection(locale);
    return context.createConfigurationContext(configuration);
}

This, along with STEP 1, sets the correct Locale in every Activity of your app for API level 26 and above.

One more step, however, is required for setting the language direction correctly ...

STEP 3:

In the onCreate() of your BaseActivity, add the following code:

@Override
protected void onCreate(Bundle savedInstanceState) {

    ....
    ....

    // yup, it's a legit bug ... :)
    if (Build.VERSION.SDK_INT >= 26) {
        getWindow().getDecorView().setLayoutDirection(Utils.isRTL()
                ? View.LAYOUT_DIRECTION_RTL : View.LAYOUT_DIRECTION_LTR);


    }

    ....
    ....
}

where the isRTL() function is defined as follows:

public static boolean isRTL(){
    return TextUtilsCompat.getLayoutDirectionFromLocale(Locale.getDefault()) == View.LAYOUT_DIRECTION_RTL;
}

The above steps should take care of all issues (at least regarding setting the Locale and text direction) on all extant versions of Android.