How to change language of app when user selects language?

Question

It's excerpt for the webpage: http://android.programmerguru.com/android-localization-at-runtime/

It's simple to change the language of your app upon user selects it from list of languages. Have a method like below which accepts the locale as String (like 'en' for English, 'hi' for hindi), configure the locale for your App and refresh your current activity to reflect the change in language. The locale you applied will not be changed until you manually change it again.

public void setLocale(String lang) { 
    Locale myLocale = new Locale(lang); 
    Resources res = getResources(); 
    DisplayMetrics dm = res.getDisplayMetrics(); 
    Configuration conf = res.getConfiguration(); 
    conf.locale = myLocale; 
    res.updateConfiguration(conf, dm); 
    Intent refresh = new Intent(this, AndroidLocalize.class); 
    finish();
    startActivity(refresh); 
} 

Make sure you imported following packages:

import java.util.Locale; 
import android.os.Bundle; 
import android.app.Activity; 
import android.content.Intent; 
import android.content.res.Configuration; 
import android.content.res.Resources; 
import android.util.DisplayMetrics; 

add in manifest to activity android:configChanges="locale|orientation"

Good solutions explained pretty well here. But Here is one more.

Create your own CustomContextWrapper class extending ContextWrapper and use it to change Locale setting for the complete application. Here is a GIST with usage.

And then call the CustomContextWrapper with saved locale identifier e.g. 'hi' for Hindi language in activity lifecycle method attachBaseContext. Usage here:

@Override
protected void attachBaseContext(Context newBase) {
    // fetch from shared preference also save the same when applying. Default here is en = English
    String language = MyPreferenceUtil.getInstance().getString("saved_locale", "en");
    super.attachBaseContext(MyContextWrapper.wrap(newBase, language));
}

all the above @Uday's code is perfect but only one thing is missing(default config in build.gradle)

public void setLocale(String lang) { 
Locale myLocale = new Locale(lang); 
Resources res = getResources(); 
DisplayMetrics dm = res.getDisplayMetrics(); 
Configuration conf = res.getConfiguration(); 
conf.locale = myLocale; 
res.updateConfiguration(conf, dm); 
Intent refresh = new Intent(this, AndroidLocalize.class); 
finish();
startActivity(refresh); 

}

Mine was not working just because the languages were not mentioned in the config file(build.gradle)

 defaultConfig {
    resConfigs "en", "hi", "kn"
}

after that, all languages started running

You should either remove android:configChanges="locale" from manifest, which will cause activity to reload, or override onConfigurationChanged method:

@Override
public void onConfigurationChanged(Configuration newConfig) {
super.onConfigurationChanged(newConfig);
    // your code here, you can use newConfig.locale if you need to check the language
    // or just re-set all the labels to desired string resource
}

Kotlin solution using context extension

fun Context.applyNewLocale(locale: Locale): Context {
    val config = this.resources.configuration
    val sysLocale = if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
        config.locales.get(0)
    } else {
        //Legacy
        config.locale
    }
    if (sysLocale.language != locale.language) {
        Locale.setDefault(locale)
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
            config.setLocale(locale)
        } else {
            //Legacy
            config.locale = locale
        }
        resources.updateConfiguration(config, resources.displayMetrics)
    }
    return this
}

Usage

override fun attachBaseContext(newBase: Context?) {
    super.attachBaseContext(newBase?.applyNewLocale(Locale("es", "MX")))
}

Those who getting the version issue try this code ..

public static void switchLocal(Context context, String lcode, Activity activity) {
        if (lcode.equalsIgnoreCase(""))
            return;
        Resources resources = context.getResources();
        Locale locale = new Locale(lcode);
        Locale.setDefault(locale);
        android.content.res.Configuration config = new 
        android.content.res.Configuration();
        config.locale = locale;
        resources.updateConfiguration(config, resources.getDisplayMetrics());
        //restart base activity 
        activity.finish();
        activity.startActivity(activity.getIntent());
    }

Udhay's sample code works well. Except the question of Sofiane Hassaini and Chirag SolankI, for the re-entrance, it doesn't work. I try to call Udhay's code without restart the activity in onCreate() , before super.onCreate(savedInstanceState);. Then it is OK! Only a little problem, the menu strings still not changed to the set Locale.

    public void setLocale(String lang) { //call this in onCreate()
      Locale myLocale = new Locale(lang); 
      Resources res = getResources(); 
      DisplayMetrics dm = res.getDisplayMetrics(); 
      Configuration conf = res.getConfiguration(); 
      conf.locale = myLocale; 
      res.updateConfiguration(conf, dm); 
      //Intent refresh = new Intent(this, AndroidLocalize.class); 
      //startActivity(refresh); 
      //finish();
    }