Navigation Component & Safe Args

# gradle/libs.versions.toml
navigation = "2.8.5"
androidx-navigation-fragment-ktx = { group = "androidx.navigation", name = "navigation-fragment-ktx", version.ref = "navigation" }
androidx-navigation-ui-ktx = { group = "androidx.navigation", name = "navigation-ui-ktx", version.ref = "navigation" }

// app/build.gradle.kts
implementation(libs.androidx.navigation.fragment.ktx)
implementation(libs.androidx.navigation.ui.ktx)

<?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"
    android:id="@+id/nav_graph"
    app:startDestination="@id/notesFragment">

    <!-- Open the editor from anywhere (FAB, list item) -->
    <action
        android:id="@+id/action_global_editor"
        app:destination="@id/editorFragment"
        app:enterAnim="@anim/nav_default_enter_anim"
        app:exitAnim="@anim/nav_default_exit_anim"
        app:popEnterAnim="@anim/nav_default_pop_enter_anim"
        app:popExitAnim="@anim/nav_default_pop_exit_anim" />

    <fragment
        android:id="@+id/notesFragment"
        android:name="com.codingeasily.studentdiary.ui.notes.NotesFragment"
        android:label="@string/app_name" />

    <!-- The same list fragment, reused with different arguments -->
    <fragment
        android:id="@+id/favoritesFragment"
        android:name="com.codingeasily.studentdiary.ui.notes.NoteListFragment"
        android:label="@string/menu_favourites">
        <argument
            android:name="filter"
            android:defaultValue="FAVORITES"
            app:argType="string" />
    </fragment>

    <fragment
        android:id="@+id/subjectsFragment"
        android:name="com.codingeasily.studentdiary.ui.subjects.SubjectsFragment"
        android:label="@string/menu_subjects">
        <action
            android:id="@+id/action_subjects_to_subjectNotes"
            app:destination="@id/subjectNotesFragment" />
    </fragment>

    <fragment
        android:id="@+id/subjectNotesFragment"
        android:name="com.codingeasily.studentdiary.ui.notes.NoteListFragment"
        android:label="{subject}">
        <argument
            android:name="filter"
            android:defaultValue="SUBJECT"
            app:argType="string" />
        <argument
            android:name="subject"
            app:argType="string" />
    </fragment>

    <fragment
        android:id="@+id/statsFragment"
        android:name="com.codingeasily.studentdiary.ui.stats.StatsFragment"
        android:label="@string/menu_stats" />

    <fragment
        android:id="@+id/settingsFragment"
        android:name="com.codingeasily.studentdiary.ui.settings.SettingsFragment"
        android:label="@string/menu_settings" />

    <fragment
        android:id="@+id/helpFragment"
        android:name="com.codingeasily.studentdiary.ui.help.HelpFragment"
        android:label="@string/menu_help" />

    <fragment
        android:id="@+id/editorFragment"
        android:name="com.codingeasily.studentdiary.ui.editor.AddEditNoteFragment"
        android:label="@string/note">
        <argument
            android:name="noteId"
            android:defaultValue="-1L"
            app:argType="long" />
    </fragment>
</navigation>

<!-- activity_main.xml (Student Diary, part) -->
<androidx.fragment.app.FragmentContainerView
    android:id="@+id/nav_host"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="match_parent"
    android:layout_height="0dp"
    android:layout_weight="1"
    app:defaultNavHost="true"
    app:navGraph="@navigation/nav_graph" />

// Student Diary – NoteListFragment: open the editor for a note
findNavController().navigate(R.id.action_global_editor, bundleOf("noteId" to note.id))

// MainActivity – FAB opens an empty editor (noteId keeps its default -1L)
binding.fab.setOnClickListener { navController.navigate(R.id.action_global_editor) }

// SubjectsFragment – open notes of one subject
findNavController().navigate(
    R.id.action_subjects_to_subjectNotes,
    bundleOf("filter" to "SUBJECT", "subject" to item.subject)
)

// Go back
findNavController().navigateUp()

// AddEditNoteFragment
val noteId = arguments?.getLong("noteId", -1L) ?: -1L
if (noteId != -1L) loadNote(noteId) else showEmptyForm()

// build.gradle.kts (root)
plugins {
    // ...
    id("androidx.navigation.safeargs.kotlin") version "2.8.5" apply false
}

// app/build.gradle.kts
plugins {
    // ...
    id("androidx.navigation.safeargs.kotlin")
}

// nav_graph.xml has the global action  action_global_editor  →  editorFragment
// and editorFragment declares <argument android:name="noteId" app:argType="long" android:defaultValue="-1L"/>

// Generated for global actions: NavGraphDirections (named after the graph id "nav_graph")
val action = NavGraphDirections.actionGlobalEditor(noteId = note.id)
findNavController().navigate(action)

// Generated for the destination class: AddEditNoteFragmentArgs
private val args: AddEditNoteFragmentArgs by navArgs()
val noteId: Long = args.noteId        // a Long – checked by the compiler

// MainActivity (Student Diary)
val navHost = supportFragmentManager.findFragmentById(R.id.nav_host) as NavHostFragment
navController = navHost.navController
appBarConfiguration = AppBarConfiguration(topLevelIds, binding.drawerLayout)
setupActionBarWithNavController(navController, appBarConfiguration)   // title + ← / ☰

override fun onSupportNavigateUp(): Boolean =
    navController.navigateUp(appBarConfiguration) || super.onSupportNavigateUp()

// react to screen changes (hide bottom bar on the editor)
navController.addOnDestinationChangedListener { _, destination, _ ->
    binding.bottomNav.isVisible = destination.id in bottomScreens
}