Programmatically change language in Android-application

Sometimes it is necessary in the application provide an opportunity the user to change the language of the application, regardless of the locale device. In this article I will show you how to do it.

Preparing resources

Create the string resources for four languages: English, Russian, French and German.

Source code values/strings.xml (English, Default)

<resources>

    <string name="app_name">ChangeLocaleExample</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>

Source code values-ru/strings.xml (Russian)

<resources>

    <string name="hello_world">Привет, Мир</string>

    <string name="btn_en">Английский</string>

    <string name="btn_ru">Русский</string>

    <string name="btn_de">Немецкий</string>

    <string name="btn_fr">Французский</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">Français</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">Französisch</string>

</resources>

Layout application will consist of four buttons that change the language of the application and the text box to display the greeting line:

<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>

Developing an application

Add attributes to our Activity.

• UI elements:

private TextView txt_hello;

private Button btn_en, btn_ru, btn_fr, btn_de;

• Current local application:

private Locale myLocale;

Develop necessary methods to change the language in the application.

• Changing the language in the application:

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();
}

• Save the current locale:

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();
}

• Loading a saved locale:

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

• Updating the UI elements of the current screen (you need to update only the screen in which a change of locale): 

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);
}

Add events to the buttons. For this implement OnClickListener interface for our Activity (implements OnClickListener). And implement the method onClick().

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);
 }

Finally, consistent with the work with the change of language in the method onCreate () of our Activity:

protected void onCreate(Bundle savedInstanceState) {
  super.onCreate(savedInstanceState);
  setContentView(R.layout.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();
 }

Links

• The source codes of this project can be downloaded here: zip