Navigation graph

nav_graph.xml

<?xml version="1.0" encoding="utf-8"?>
<navigation 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:id="@+id/nav_graph"
   app:startDestination="@id/welcomeFragment">
   <fragment
       android:id="@+id/welcomeFragment"
       android:name="com.beatrice.bookfinder.WelcomeFragment"
       android:label="fragment_welcome"
       tools:layout="@layout/fragment_welcome" >
       <action
           android:id="@+id/action_welcomeFragment_to_loginFragment"
           app:destination="@id/loginFragment"/>
   </fragment>
   <fragment
       android:id="@+id/loginFragment"
       android:name="com.beatrice.bookfinder.LoginFragment"
       android:label="fragment_login"
       tools:layout="@layout/fragment_login" >
       <action
           android:id="@+id/action_loginFragment_to_mainFragment"
           app:destination="@id/mainFragment" />
   </fragment>
</navigation>