Basic outline of Resources/Activity/Fragment connection:

First, we make SettingsActivity. Then, we create SettingsFragment, in which we write addPreferencesFromResource(R.xml.pref_settings); to connect it with a resource we created in xml resource directory.

Finally, we make root layout of activity_settings.xml a fragment, specifically SettingsFragment, with android:name="com.example.android.myapp.SettingsFragment"

Important note: Must not forget adding a style in styles.xml. Otherwise, app will crash.