In this tutorial, we will know that how to use multiple language in a single application . We are using four language to show our contents such as English, Russian, German, French. Follow below steps.

Step 1- Prepare string resource for the four language like English,French,Russian and German.

<resources>
    <string name="app_name">MultiLanguage</string>
    <string name="hello_world">Hello World</string>
    <string name="btn_en">English</string>
    <string name="btn_ru">Russian</string>
    <string name="btn_de">German</string>
    <string name="btn_fr">French</string>
</resources>

Step2- Created string.xml file for all four language

Source code values-ru/strings.xml (Russian)
    <resources>
    <string name="hello_world">, </string>
    <string name="btn_en"></string>
    <string name="btn_ru"></string>
    <string name="btn_de"></string>
    <string name="btn_fr"></string>
    </resources>
    
    Source code values-fr/strings.xml (French)
    <resources>
    <string name="hello_world">Bonjour monde</string>
    <string name="btn_en">Anglais</string>
    <string name="btn_ru">Russie</string>
    <string name="btn_de">Allemand</string>
    <string name="btn_fr">Franais</string>
    </resources>
   
   Source code values-de/strings.xml (German)
    <resources>
    <string name="hello_world">Hallo Welt</string>
    <string name="btn_en">Englisch</string>
    <string name="btn_ru">Russisch</string>
    <string name="btn_de">Deutsch</string>
    <string name="btn_fr">Franzsisch</string>
    </resources>

For English , it will pick default content from string.xml resource file

Step3- Create an activity_main.xml file

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >
   
  <TextView
    android:id="@+id/txt_hello"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:gravity="center"
    android:text="@string/hello_world" />
   
 <LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:orientation="horizontal"
    android:gravity="center">
    
<Button
    android:id="@+id/btn_en"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:text="@string/btn_en" />
   
 <Button
    android:id="@+id/btn_ru"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:text="@string/btn_ru" />
   
 <Button
    android:id="@+id/btn_de"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:text="@string/btn_de" />
   
 <Button
    android:id="@+id/btn_fr"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_weight="1"
    android:text="@string/btn_fr" />
    </LinearLayout>
    </LinearLayout>

Step4- MainActivity.java

Finally, we have crated activity to do complete functionality.

 public class MainActivity extends AppCompatActivity implements View.OnClickListener{
    private TextView txt_hello;
    private Button btn_en, btn_ru, btn_fr, btn_de;
    private Locale myLocale;
    

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    
    this.txt_hello = (TextView)findViewById(R.id.txt_hello);
    this.btn_en = (Button) findViewById(R.id.btn_en);
    this.btn_ru = (Button) findViewById(R.id.btn_ru);
    this.btn_fr = (Button)findViewById(R.id.btn_fr);
    this.btn_de = (Button)findViewById(R.id.btn_de);
    this.btn_en.setOnClickListener(this);
    this.btn_ru.setOnClickListener(this);
    this.btn_fr.setOnClickListener(this);
    this.btn_de.setOnClickListener(this);
    loadLocale();
    }
   

    public void loadLocale(){
    String langPref = "Language";
    SharedPreferences prefs = getSharedPreferences("CommonPrefs", Activity.MODE_PRIVATE);
    String language = prefs.getString(langPref, "");
    changeLang(language);
    }
    

   public void saveLocale(String lang)
    {
    String langPref = "Language";
    SharedPreferences prefs = getSharedPreferences("CommonPrefs", Activity.MODE_PRIVATE);
    SharedPreferences.Editor editor = prefs.edit();
    editor.putString(langPref, lang);
    editor.commit();
    }
   

   public void changeLang(String lang) {
    if (lang.equalsIgnoreCase(""))
    return;
    myLocale = new Locale(lang);
    saveLocale(lang);
    Locale.setDefault(myLocale);
    android.content.res.Configuration config = new android.content.res.Configuration();
    config.locale = myLocale;
    getBaseContext().getResources().updateConfiguration(config, getBaseContext().getResources().getDisplayMetrics());
    updateTexts();
    }
    

   private void updateTexts(){
    txt_hello.setText(R.string.hello_world);
    btn_en.setText(R.string.btn_en);
    btn_ru.setText(R.string.btn_ru);
    btn_fr.setText(R.string.btn_fr);
    btn_de.setText(R.string.btn_de);
    }
    

   @Override
    public void onClick(View v) {
    String lang = "en";
    switch (v.getId()) {
    case R.id.btn_en:
    lang = "en";
    break;
    case R.id.btn_ru:
    lang = "ru";
    break;
    case R.id.btn_de:
    lang = "de";
    break;
    case R.id.btn_fr:
    lang = "fr";
    break;
    default:
    break;
    }
   
   changeLang(lang);
    }
    

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