Tip

Adjust Navigation Graph

gradle(app)

dependencies {
    def nav_version = "2.3.3"

    implementation "androidx.navigation:navigation-fragment-ktx:$nav_version"
    implementation "androidx.navigation:navigation-ui-ktx:$nav_version"
    
    ...
}

File - New - Android Resouce Directory

New Resouce Directory - Resouce Type - navigation - OK

MainActivity.kt

class MainActivity : AppCompatActivity(R.layout.activity_main) {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)

        val navHostFragment = supportFragmentManager
                .findFragmentById(R.id.nav_host_fragment) as NavHostFragment
        val navController = navHostFragment.navController

        setupActionBarWithNavController(navController)
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.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=".MainActivity">

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/nav_host_fragment"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navGraph="@navigation/nav_graph" />

</androidx.constraintlayout.widget.ConstraintLayout>

nav_graph.xml [startDestination을 지정해 주지 않으면 오류가 난다.]

<?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/startFragment">
    
    <fragment
        android:id="@+id/startFragment"
        android:name="com.example.damoa.StartFragment"
        android:label="fragment_start"
        tools:layout="@layout/fragment_start" />

</navigation>

Add Fragment

File - New - Fragment

 

Hide ActionBar(TopBar)

in Fragment.kt

override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
	//Hide Action Bar
	(activity as AppCompatActivity?)!!.supportActionBar!!.hide()
	// Inflate the layout for this fragment
	return inflater.inflate(R.layout.fragment_start, container, false)
}