Change app language programmatically in Android

Question

Is it possible to change the language of an app programmatically while still using Android resources?

If not, is it possible to request a resource in an specific language?

I would like to let the user change the language of the app from the app.

Solution 1

It's possible. You can set the locale. However, I would not recommend that. We've tried it at early stages, it's basically fighting the system.

We have the same requirement for changing the language but decided to settle to the fact that UI should be same as phone UI. It was working via setting locale but was too buggy. And you have to set it every time you enter activity (each activity) from my experience. here is a code if you still need this (again, I don't recommend that)

Resources res = context.getResources();
// Change locale settings in the app.
DisplayMetrics dm = res.getDisplayMetrics();
android.content.res.Configuration conf = res.getConfiguration();
conf.setLocale(new Locale(language_code.toLowerCase())); // API 17+ only.
// Use conf.locale = new Locale(...) if targeting lower versions
res.updateConfiguration(conf, dm);

If you have language specific content - you can change that base on the setting.

---

update on 26th of march 2020

    public static void setLocale(Activity activity, String languageCode) {
        Locale locale = new Locale(languageCode);
        Locale.setDefault(locale);
        Resources resources = activity.getResources();
        Configuration config = resources.getConfiguration();
        config.setLocale(locale);
        resources.updateConfiguration(config, resources.getDisplayMetrics());
    }

• NOTES: Language code cannot got '-' & must be 2 small case letter only

Solution 2

This code really works:

fa = Persian, en = English

• NOTES: Language code cannot got '-' & must be 2 small case letter only

Enter your language code in languageToLoad variable:

import android.app.Activity;
import android.content.res.Configuration;
import android.os.Bundle;

public class Main extends Activity {
  /** Called when the activity is first created. */
  @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

    String languageToLoad  = "fa"; // your language
    Locale locale = new Locale(languageToLoad); 
    Locale.setDefault(locale);
    Configuration config = new Configuration();
    config.locale = locale;
    getBaseContext().getResources().updateConfiguration(config, 
      getBaseContext().getResources().getDisplayMetrics());
    this.setContentView(R.layout.main);
  }
}

---

UPDATE on Jun 2021(Kotlin):

class Main : Activity() {
    // Called when the activity is first created.
    public override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        
        val config = resources.configuration
        val lang = "fa" // your language code
        val locale = Locale(lang)
        Locale.setDefault(locale)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1)
            config.setLocale(locale)
        else
            config.locale = locale

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N)
            createConfigurationContext(config)
        resources.updateConfiguration(config, resources.displayMetrics)

        this.setContentView(R.layout.main)
    }
}

Solution 3

I was looking for a way to change the system language programmatically. While I fully understand that a normal application should never do that and instead either:

• the user should be pointed(through an intent) to the system settings to change it manually
• the application should handle its localization on its own just like described in the answer of Alex

there was a need to really change the language of the system programmtically.

This is undocumented API and thus should not be used for market/end-user applications!

Anyway heres the solution i found:

  Locale locale = new Locale(targetLocaleAsString);

  Class amnClass = Class.forName("android.app.ActivityManagerNative");
  Object amn = null;
  Configuration config = null;

  // amn = ActivityManagerNative.getDefault();
  Method methodGetDefault = amnClass.getMethod("getDefault");
  methodGetDefault.setAccessible(true);
  amn = methodGetDefault.invoke(amnClass);

  // config = amn.getConfiguration();
  Method methodGetConfiguration = amnClass.getMethod("getConfiguration");
  methodGetConfiguration.setAccessible(true);
  config = (Configuration) methodGetConfiguration.invoke(amn);

  // config.userSetLocale = true;
  Class configClass = config.getClass();
  Field f = configClass.getField("userSetLocale");
  f.setBoolean(config, true);

  // set the locale to the new value
  config.locale = locale;

  // amn.updateConfiguration(config);
  Method methodUpdateConfiguration = amnClass.getMethod("updateConfiguration", Configuration.class);
  methodUpdateConfiguration.setAccessible(true);
  methodUpdateConfiguration.invoke(amn, config);

Solution 4

If you want to mantain the language changed over all your app you have to do two things.

First, create a base Activity and make all your activities extend from this:

public class BaseActivity extends AppCompatActivity {

    private Locale mCurrentLocale;

    @Override
    protected void onStart() {
        super.onStart();

        mCurrentLocale = getResources().getConfiguration().locale;
    }

    @Override
    protected void onRestart() {
        super.onRestart();
        Locale locale = getLocale(this);

        if (!locale.equals(mCurrentLocale)) {

            mCurrentLocale = locale;
            recreate();
        }
    }

    public static Locale getLocale(Context context){
        SharedPreferences sharedPreferences = PreferenceManager.getDefaultSharedPreferences(context);

        String lang = sharedPreferences.getString("language", "en");
        switch (lang) {
            case "English":
                lang = "en";
                break;
            case "Spanish":
                lang = "es";
                break;
        }
        return new Locale(lang);
    }
}

Note that I save the new language in a sharedPreference.

Second, create an extension of Application like this:

    public class App extends Application {

    @Override
    public void onCreate() {
        super.onCreate();
        setLocale();
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        setLocale();
    }

    private void setLocale() {

        final Resources resources = getResources();
        final Configuration configuration = resources.getConfiguration();
        final Locale locale = getLocale(this);
        if (!configuration.locale.equals(locale)) {
            configuration.setLocale(locale);
            resources.updateConfiguration(configuration, null);
        }
    }
}

Note that getLocale() it's the same as above.

That's all! I hope this can help somebody.

Solution 5

According to this article. You will need to download LocaleHelper.java referenced in that article.

1. Create MyApplication class that will extends Application
2. Override attachBaseContext() to update language.

3. Register this class in manifest.

   public class MyApplication extends Application {
      @Override
      protected void attachBaseContext(Context base) {
       super.attachBaseContext(LocaleHelper.onAttach(base, "en"));
      }
   }
   
   <application
        android:name="com.package.MyApplication"
        .../>
   

4. Create BaseActivity and override onAttach() to update language. Needed for Android 6+

   public class BaseActivity extends Activity {
     @Override
     protected void attachBaseContext(Context base) {
       super.attachBaseContext(LocaleHelper.onAttach(base));
     }
   }
   

5. Make all activities on your app extends from BaseActivity.

   public class LocaleHelper {
   
   private static final String SELECTED_LANGUAGE = "Locale.Helper.Selected.Language";
   
   public static Context onAttach(Context context) {
       String lang = getPersistedData(context, Locale.getDefault().getLanguage());
       return setLocale(context, lang);
   }
   
   public static Context onAttach(Context context, String defaultLanguage) {
       String lang = getPersistedData(context, defaultLanguage);
       return setLocale(context, lang);
   }
   
   public static String getLanguage(Context context) {
       return getPersistedData(context, Locale.getDefault().getLanguage());
   }
   
   public static Context setLocale(Context context, String language) {
       persist(context, language);
   
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
           return updateResources(context, language);
       }
   
       return updateResourcesLegacy(context, language);
   }
   
   private static String getPersistedData(Context context, String defaultLanguage) {
       SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
       return preferences.getString(SELECTED_LANGUAGE, defaultLanguage);
   }
   
   private static void persist(Context context, String language) {
       SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
       SharedPreferences.Editor editor = preferences.edit();
   
       editor.putString(SELECTED_LANGUAGE, language);
       editor.apply();
   }
   
   @TargetApi(Build.VERSION_CODES.N)
   private static Context updateResources(Context context, String language) {
       Locale locale = new Locale(language);
       Locale.setDefault(locale);
   
       Configuration configuration = context.getResources().getConfiguration();
       configuration.setLocale(locale);
       configuration.setLayoutDirection(locale);
   
       return context.createConfigurationContext(configuration);
   }
   
   @SuppressWarnings("deprecation")
   private static Context updateResourcesLegacy(Context context, String language) {
       Locale locale = new Locale(language);
       Locale.setDefault(locale);
   
       Resources resources = context.getResources();
   
       Configuration configuration = resources.getConfiguration();
       configuration.locale = locale;
       if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
           configuration.setLayoutDirection(locale);
       }
   
       resources.updateConfiguration(configuration, resources.getDisplayMetrics());
   
       return context;
   }
   }
   

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