Question

How we can change the languages as per selection done from the language menu.

Answer 1

In your res folder, you should have a folder called values. Inside that folder, place a strings.xml file.

The strings.xml files should contain something like this

<resources>
    <string name="app_name">My App Name</string>
    <string name="someText">someText in default language</string>
    <string name="nonTranslatedText">someText only in default language</string>
</resources>

If you want to support other languages, just create additional values folders inside res, also containing a string.xml file, containing the translations.

So if you want to support Dutch for example, create a strings.xml in a values-nl folder, containing this :

<resources>
    <string name="app_name">My App Name in Dutch</string>
    <string name="someText">someText in Dutch</string>
</resources>

The translations will be automatically picked up by Android when the user switches languages. If no translations can be found for the given language (ex: the nonTranslatedText string), it will default to the ones found in res/values/strings.xml.

You can refer to these strings in layouts like this :

<Button android:id="@+id/someId" style="@style/someStyle" android:text="@string/someText"/> 

Or in java objects like this :

context.getString(R.string.someText);