Just recently context.getResources().updateConfiguration() has been deprecated in Android API 25 and it is advised to use context.createConfigurationContext() instead.

Does anyone know how createConfigurationContext can be used to override android system locale?

before this would be done by:

Configuration config = getBaseContext().getResources().getConfiguration();
config.setLocale(locale);
context.getResources().updateConfiguration(config,
                                 context.getResources().getDisplayMetrics());

Solution 1

Inspired by Calligraphy, I ended up creating a context wrapper. In my case, I need to overwrite system language to provide my app users with the option of changing app language but this can be customized with any logic that you need to implement.

    import android.annotation.TargetApi;
    import android.content.Context;
    import android.content.ContextWrapper;
    import android.content.res.Configuration;
    import android.os.Build;
    
    import java.util.Locale;
    
    public class MyContextWrapper extends ContextWrapper {

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

    @SuppressWarnings("deprecation")
    public static ContextWrapper wrap(Context context, String language) {
        Configuration config = context.getResources().getConfiguration();
        Locale sysLocale = null;
        if (Build.VERSION.SDK_INT > Build.VERSION_CODES.N) {
            sysLocale = getSystemLocale(config);
        } else {
            sysLocale = getSystemLocaleLegacy(config);
        }
        if (!language.equals("") && !sysLocale.getLanguage().equals(language)) {
            Locale locale = new Locale(language);
            Locale.setDefault(locale);
            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
                setSystemLocale(config, locale);
            } else {
                setSystemLocaleLegacy(config, locale);
            }
            
        }
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
             context = context.createConfigurationContext(config);
        } else {
             context.getResources().updateConfiguration(config, context.getResources().getDisplayMetrics());
            }
        return new MyContextWrapper(context);
    }

    @SuppressWarnings("deprecation")
    public static Locale getSystemLocaleLegacy(Configuration config){
        return config.locale;
    }

    @TargetApi(Build.VERSION_CODES.N)
    public static Locale getSystemLocale(Configuration config){
        return config.getLocales().get(0);
    }

    @SuppressWarnings("deprecation")
    public static void setSystemLocaleLegacy(Configuration config, Locale locale){
        config.locale = locale;
    }

    @TargetApi(Build.VERSION_CODES.N)
    public static void setSystemLocale(Configuration config, Locale locale){
        config.setLocale(locale);
    }
}

and to inject your wrapper, in every activity add the following code:

@Override
protected void attachBaseContext(Context newBase) {
    super.attachBaseContext(MyContextWrapper.wrap(newBase,"fr"));
}

UPDATE 22/12/2020 After android Material library implementation of ContextThemeWrapper to support dark mode, the language setting would break and language setting is lost. After months of head scratching, problem was resolved by adding the following code to Activity and Fragment onCreate method

Context context = MyContextWrapper.wrap(this/*in fragment use getContext() instead of this*/, "fr");
   getResources().updateConfiguration(context.getResources().getConfiguration(), context.getResources().getDisplayMetrics());

UPDATE 10/19/2018 Sometimes after orientation change, or activity pause/resume the Configuration object resets to default system Configuration and in result we will see the app displaying English "en" text even though we wrapped the context with French "fr" locale. Therefore and as a good practice, never retain the Context/Activity object in a global variable in activities or fragments.

furthermore, create and use the following in a MyBaseFragment or MyBaseActivity:

public Context getMyContext(){
    return MyContextWrapper.wrap(getContext(),"fr");
}

This practice will provide you with 100% bug free solution.

Solution 2

Probably like this :

Configuration overrideConfiguration = getBaseContext().getResources().getConfiguration();
overrideConfiguration.setLocales(LocaleList);
Context context  = createConfigurationContext(overrideConfiguration);
Resources resources = context.getResources();

Bonus : A blog article who use createConfigurationContext()

Solution 3

I have resolved this without creating any custom ContextWrapper.

First I created an extension function

fun Context.setAppLocale(language: String): Context {
    val locale = Locale(language)
    Locale.setDefault(locale)
    val config = resources.configuration
    config.setLocale(locale)
    config.setLayoutDirection(locale)
    return createConfigurationContext(config)
}

Then in the activity's attachBaseContext method, simply replacing the context with the new one.

override fun attachBaseContext(newBase: Context) {
  super.attachBaseContext(ContextWrapper(newBase.setAppLocale("bn")))
}

Solution 4

Inspired by Calligraphy & Mourjan & myself, i created this.

first you must create a subclass of Application:

public class MyApplication extends Application {
    private Locale locale = null;

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

        SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(this);

        Configuration config = getBaseContext().getResources().getConfiguration();

        String lang = preferences.getString(getString(R.string.pref_locale), "en");
        String systemLocale = getSystemLocale(config).getLanguage();
        if (!"".equals(lang) && !systemLocale.equals(lang)) {
            locale = new Locale(lang);
            Locale.setDefault(locale);
            setSystemLocale(config, locale);
            updateConfiguration(config);
        }
    }

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        if (locale != null) {
            setSystemLocale(newConfig, locale);
            Locale.setDefault(locale);
            updateConfiguration(newConfig);
        }
    }

    @SuppressWarnings("deprecation")
    private static Locale getSystemLocale(Configuration config) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            return config.getLocales().get(0);
        } else {
            return config.locale;
        }
    }

    @SuppressWarnings("deprecation")
    private static void setSystemLocale(Configuration config, Locale locale) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            config.setLocale(locale);
        } else {
            config.locale = locale;
        }
    }

    @SuppressWarnings("deprecation")
    private void updateConfiguration(Configuration config) {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
            getBaseContext().createConfigurationContext(config);
        } else {
            getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());
        }
    }
}

then you need set this to your AndroidManifest.xml application tag:

<application
    ...
    android:name="path.to.your.package.MyApplication"
    >

and add this to your AndroidManifest.xml activity tag.

<activity
    ...
    android:configChanges="locale"
    >

note that pref_locale is a string resource like this:

<string name="pref_locale">fa</string>

and hardcode "en" is default lang if pref_locale is not setted

Solution 5

Here is no 100% working solution. You need to use both createConfigurationContext and applyOverrideConfiguration. Otherwise even if you replace baseContext in every activity with new configuration, activity would still use Resources from ContextThemeWrapper with old locale.

So here is mine solution which works up to API 29:

Subclass your MainApplication class from:

abstract class LocalApplication : Application() {

    override fun attachBaseContext(base: Context) {
        super.attachBaseContext(
            base.toLangIfDiff(
                PreferenceManager
                    .getDefaultSharedPreferences(base)
                    .getString("langPref", "sys")!!
             )
        )
    }
}

Also every Activity from:

abstract class LocalActivity : AppCompatActivity() {

    override fun attachBaseContext(newBase: Context) {
        super.attachBaseContext(            
            PreferenceManager
                .getDefaultSharedPreferences(base)
                    .getString("langPref", "sys")!!
        )
    }

    override fun applyOverrideConfiguration(overrideConfiguration: Configuration) {
        super.applyOverrideConfiguration(baseContext.resources.configuration)
    }
}

Add LocaleExt.kt with next extension functions:

const val SYSTEM_LANG = "sys"
const val ZH_LANG = "zh"
const val SIMPLIFIED_CHINESE_SUFFIX = "rCN"


private fun Context.isAppLangDiff(prefLang: String): Boolean {
    val appConfig: Configuration = this.resources.configuration
    val sysConfig: Configuration = Resources.getSystem().configuration

    val appLang: String = appConfig.localeCompat.language
    val sysLang: String = sysConfig.localeCompat.language

    return if (SYSTEM_LANG == prefLang) {
        appLang != sysLang
    } else {
        appLang != prefLang
                || ZH_LANG == prefLang
    }
}

fun Context.toLangIfDiff(lang: String): Context =
    if (this.isAppLangDiff(lang)) {
        this.toLang(lang)
    } else {
        this
    }

@Suppress("DEPRECATION")
fun Context.toLang(toLang: String): Context {
    val config = Configuration()

    val toLocale = langToLocale(toLang)

    Locale.setDefault(toLocale)
    if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        config.setLocale(toLocale)

        val localeList = LocaleList(toLocale)
        LocaleList.setDefault(localeList)
        config.setLocales(localeList)
    } else {
        config.locale = toLocale
    }

    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
        config.setLayoutDirection(toLocale)
        this.createConfigurationContext(config)
    } else {
        this.resources.updateConfiguration(config, this.resources.displayMetrics)
        this
    }
}

/**
 * @param toLang - two character representation of language, could be "sys" - which represents system's locale
 */
fun langToLocale(toLang: String): Locale =
    when {
        toLang == SYSTEM_LANG ->
            Resources.getSystem().configuration.localeCompat

        toLang.contains(ZH_LANG) -> when {
            toLang.contains(SIMPLIFIED_CHINESE_SUFFIX) ->
                Locale.SIMPLIFIED_CHINESE
            Build.VERSION.SDK_INT >= Build.VERSION_CODES.N ->
                Locale(ZH_LANG, "Hant")
            else ->
                Locale.TRADITIONAL_CHINESE
        }

        else -> Locale(toLang)
    }

@Suppress("DEPRECATION")
private val Configuration.localeCompat: Locale
    get() = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        this.locales.get(0)
    } else {
        this.locale
    }

Add to your res/values/arrays.xml your supported languages in array:

<string-array name="lang_values" translatable="false">
    <item>sys</item> <!-- System default -->
    <item>ar</item>
    <item>de</item>
    <item>en</item>
    <item>es</item>
    <item>fa</item>
    ...
    <item>zh</item> <!-- Traditional Chinese -->
    <item>zh-rCN</item> <!-- Simplified Chinese -->
</string-array>

I want to mention:

  • Use config.setLayoutDirection(toLocale); to change layout direction when you use RTL locales like Arabic, Persian, etc.
  • "sys" in the code is a value that means "inherit system default language".
  • Here "langPref" is a key of preference where you put user current language.
  • There is no need to recreate the context if it already uses needed locale.
  • There is no need for ContextWraper as posted here, just set new context returned from createConfigurationContext as baseContext
  • This is very important! When you call createConfigurationContext you should pass configuration crated from scratch and only with Locale property set. There shouldn't be any other property set to this configuration. Because if we set some other properties for this config (orientation for example), we override that property forever, and our context no longer change this orientation property even if we rotate the screen.
  • It is not enough only to recreate activity when user selects a different language, because applicationContext will remain with old locale and it could provide unexpected behaviour. So listen to preference change and restart whole application task instead:

fun Context.recreateTask() {
    this.packageManager
        .getLaunchIntentForPackage(context.packageName)
        ?.let { intent ->
            val restartIntent = Intent.makeRestartActivityTask(intent.component)
            this.startActivity(restartIntent)
            Runtime.getRuntime().exit(0)
         }
}

Solution 6

Here's @bassel-mourjan's solution with a bit of kotlin goodness :) :

import android.annotation.TargetApi
import android.content.ContextWrapper
import android.os.Build
import java.util.*

@Suppress("DEPRECATION")
fun ContextWrapper.wrap(language: String): ContextWrapper {
    val config = baseContext.resources.configuration
    val sysLocale: Locale = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        this.getSystemLocale()
    } else {
        this.getSystemLocaleLegacy()
    }

    if (!language.isEmpty() && sysLocale.language != language) {
        val locale = Locale(language)
        Locale.setDefault(locale)

        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            this.setSystemLocale(locale)
        } else {
            this.setSystemLocaleLegacy(locale)
        }
    }

    return if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.JELLY_BEAN_MR1) {
        val context = baseContext.createConfigurationContext(config)
        ContextWrapper(context)
    } else {
        baseContext.resources.updateConfiguration(config, baseContext.resources.displayMetrics)
        ContextWrapper(baseContext)
    }

}

@Suppress("DEPRECATION")
fun ContextWrapper.getSystemLocaleLegacy(): Locale {
    val config = baseContext.resources.configuration
    return config.locale
}

@TargetApi(Build.VERSION_CODES.N)
fun ContextWrapper.getSystemLocale(): Locale {
    val config = baseContext.resources.configuration
    return config.locales[0]
}


@Suppress("DEPRECATION")
fun ContextWrapper.setSystemLocaleLegacy(locale: Locale) {
    val config = baseContext.resources.configuration
    config.locale = locale
}

@TargetApi(Build.VERSION_CODES.N)
fun ContextWrapper.setSystemLocale(locale: Locale) {
    val config = baseContext.resources.configuration
    config.setLocale(locale)
}

And here is how you use it:

override fun attachBaseContext(newBase: Context?) {
    super.attachBaseContext(ContextWrapper(newBase).wrap(defaultLocale.language))
}

Solution 7

there is a simple solution with contextWrapper here : Android N change language programatically Pay attention to the recreate() method

Solution 8

Try this:

Configuration config = getBaseContext().getResources().getConfiguration();
config.setLocale(locale);
context.createConfigurationContext(config);