((App)getApplicationContext()).changeLang(lang);

public class App extends Application {

    private Locale locale = null;

    @Override
    public void onConfigurationChanged(Configuration newConfig) {
        super.onConfigurationChanged(newConfig);
        if (locale != null) {
            Locale.setDefault(locale);
            Configuration config = new Configuration(newConfig);
            config.locale = locale;
            getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());
        }
    }

    @Override
    public void onCreate() {
        super.onCreate();
        SharedPreferences settings = PreferenceManager.getDefaultSharedPreferences(this);
        String lang = settings.getString(getString(R.string.locale_lang), "");
        changeLang(lang);
    }

    public void changeLang(String lang) {
        Configuration config = getBaseContext().getResources().getConfiguration();
        if (!"".equals(lang) && !config.locale.getLanguage().equals(lang)) {

            Editor ed = PreferenceManager.getDefaultSharedPreferences(this).edit();
            ed.putString(getString(R.string.locale_lang), lang);
            ed.commit();

            locale = new Locale(lang);
            Locale.setDefault(locale);
            Configuration conf = new Configuration(config);
            conf.locale = locale;
            getBaseContext().getResources().updateConfiguration(conf, getBaseContext().getResources().getDisplayMetrics());
        }
    }

    public String getLang(){
        return PreferenceManager.getDefaultSharedPreferences(this).getString(this.getString(R.string.locale_lang), "");
    }



}

// ...
    View radio1 = findViewById(R.id.Et);
    radio1.setOnClickListener(this);
    View radio2 = findViewById(R.id.En);
    radio2.setOnClickListener(this);
    // ...`

// ...
    public void onClick(View v1) {
            switch (v1.getId()) {

            case R.id.Et:
                languageToLoad = true;
                break;

            case R.id.En:
                languageToLoad = false;
                break;

                // ...`

//...
        public void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);

            if (YourSuperClass.languageToLoad) {
                setContentView(R.layout.youractivity);      // estonian
                setTitle(R.string.youractivity_title);
            } else {
                setContentView(R.layout.youractivityen);        // english
                setTitle(R.string.youractivity_title_en);
            }

            Intent i = getIntent();
            //...`