This tutorial will explain you how to change the language locale of your application at runtime or dynamically.
The code explained here will show you how to convert text written in English to French language using a Helper class.
Step 1: Create Separate string.xml With Translations
Here fr is the language qualifier for french language resources.
So please create two separate String.xml under res folder with following names,
By default, we we have a string.xml file under values folder. To create new translation for french language, we need to create a separate string.xml for french language under values-fr folder.
- values/string.xml
- values-fr/string.xml
Add string values to both string files as follows,
string.xml
<resources>
<string name="app_name">Change Language</string>
<string name="hello">Hello</string>
<string name="welcome">Welcome,</string>
</resources>
values-fr/string.xml
<resources>
<string name="app_name">Changer de langue</string>
<string name="hello">Bonjour</string>
<string name="welcome">Bienvenue,</string>
</resources>
Step 2: Create Locale Helper Class
Please create a Helper class called LocaleHelper in utils package. Which has all the methods to manage the language switching functionalities.
LocaleHelper.java
package devdeeds.com.changelanguage;
import android.annotation.TargetApi;
import android.content.Context;
import android.content.SharedPreferences;
import android.content.res.Configuration;
import android.content.res.Resources;
import android.os.Build;
import android.preference.PreferenceManager;
import java.util.Locale;
/**
* Created by devdeeds.com on 18/4/17.
* by Jayakrishnan P.M
*/
public class LocaleHelper {
private static final String SELECTED_LANGUAGE = "Locale.Helper.Selected.Language";
public static Context onAttach(Context context) {
String lang = getPersistedData(context, Locale.getDefault().getLanguage());
return setLocale(context, lang);
}
public static Context onAttach(Context context, String defaultLanguage) {
String lang = getPersistedData(context, defaultLanguage);
return setLocale(context, lang);
}
public static String getLanguage(Context context) {
return getPersistedData(context, Locale.getDefault().getLanguage());
}
public static Context setLocale(Context context, String language) {
persist(context, language);
if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.N) {
return updateResources(context, language);
}
return updateResourcesLegacy(context, language);
}
private static String getPersistedData(Context context, String defaultLanguage) {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
return preferences.getString(SELECTED_LANGUAGE, defaultLanguage);
}
private static void persist(Context context, String language) {
SharedPreferences preferences = PreferenceManager.getDefaultSharedPreferences(context);
SharedPreferences.Editor editor = preferences.edit();
editor.putString(SELECTED_LANGUAGE, language);
editor.apply();
}
@TargetApi(Build.VERSION_CODES.N)
private static Context updateResources(Context context, String language) {
Locale locale = new Locale(language);
Locale.setDefault(locale);
Configuration configuration = context.getResources().getConfiguration();
configuration.setLocale(locale);
return context.createConfigurationContext(configuration);
}
@SuppressWarnings("deprecation")
private static Context updateResourcesLegacy(Context context, String language) {
Locale locale = new Locale(language);
Locale.setDefault(locale);
Resources resources = context.getResources();
Configuration configuration = resources.getConfiguration();
configuration.locale = locale;
resources.updateConfiguration(configuration, resources.getDisplayMetrics());
return context;
}
}
Step 3: Activity Layout With TextViews
Create layout file with 3 TextViews and a button to change the locale. All the strings should be referred from the resource files respectively.
res/layout/activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="devdeeds.com.changelanguage.MainActivity">
<TextView
android:id="@+id/textView2"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:text="@string/hello"
android:textSize="18sp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintHorizontal_bias="0.501"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.110000014"
tools:layout_constraintLeft_creator="1"
tools:layout_constraintRight_creator="1" />
<TextView
android:id="@+id/textView"
android:layout_width="368dp"
android:layout_height="wrap_content"
android:layout_marginTop="15dp"
android:gravity="center"
android:text="@string/welcome"
android:textSize="18sp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView2"
tools:layout_constraintLeft_creator="1"
tools:layout_constraintRight_creator="1" />
<TextView
android:id="@+id/textView3"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="16dp"
android:text="@string/app_name"
android:textSize="20sp"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView" />
<Button
android:id="@+id/btnChangeLangView"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginLeft="8dp"
android:layout_marginRight="8dp"
android:layout_marginTop="24dp"
android:text="Switch To French"
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintTop_toBottomOf="@+id/textView3" />
</android.support.constraint.ConstraintLayout>
Implementation And Usage In Activity
In this activity we added a button to change the locale from English to French language.
MainActivity.java
package devdeeds.com.changelanguage;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import devdeeds.com.changelanguage.utils.LocaleHelper;
/**
* Created by devdeeds.com on 18/4/17.
* by Jayakrishnan P.M
*/
public class MainActivity extends AppCompatActivity {
private String mLanguageCode = "fr";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
//Change English to French when user clicked the button.
findViewById(R.id.btnChangeLangView).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
//Change Application level locale
LocaleHelper.setLocale(MainActivity.this, mLanguageCode);
//It is required to recreate the activity to reflect the change in UI.
recreate();
}
});
}
}
Result
