(Almost) fully programmatic creation of Jetpack Navigation graph

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"
    android:id="@+id/container"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingTop="?attr/actionBarSize">

    <com.google.android.material.bottomnavigation.BottomNavigationView
        android:id="@+id/nav_view"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        android:layout_marginStart="0dp"
        android:layout_marginEnd="0dp"
        android:background="?android:attr/windowBackground"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent" />

    <androidx.fragment.app.FragmentContainerView
        android:id="@+id/nav_host_fragment_activity_main"
        android:name="androidx.navigation.fragment.NavHostFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:defaultNavHost="true"
        app:layout_constraintBottom_toTopOf="@id/nav_view"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>

MainActivity.kt

package com.example.myapplication

import android.os.Bundle
import android.util.Log
import android.view.Menu
import com.google.android.material.bottomnavigation.BottomNavigationView
import androidx.appcompat.app.AppCompatActivity
import androidx.fragment.app.Fragment
import androidx.fragment.app.FragmentContainerView
import androidx.navigation.NavGraph
import androidx.navigation.NavGraphBuilder
import androidx.navigation.createGraph
import androidx.navigation.fragment.FragmentNavigator
import androidx.navigation.fragment.FragmentNavigatorDestinationBuilder
import androidx.navigation.fragment.NavHostFragment
import androidx.navigation.ui.AppBarConfiguration
import androidx.navigation.ui.setupActionBarWithNavController
import androidx.navigation.ui.setupWithNavController
import com.example.myapplication.ui.dashboard.DashboardFragment
import com.example.myapplication.ui.home.HomeFragment
import com.example.myapplication.ui.notifications.NotificationsFragment
import kotlin.reflect.KClass

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

        setContentView(R.layout.activity_main)

        val navView = findViewById<BottomNavigationView>(R.id.nav_view)
        val navHost = supportFragmentManager.findFragmentById(R.id.nav_host_fragment_activity_main) as NavHostFragment
        val navController = navHost.navController
        val navigator = navController.navigatorProvider.getNavigator(FragmentNavigator::class.java)

        val destFor = { klass: KClass<out Fragment>, id: String, lbl: String ->
            with(FragmentNavigatorDestinationBuilder(navigator, id, klass)) {
                label = lbl
                build()
            }
        }

        val dests = arrayOf(
            destFor(DashboardFragment::class, "navigation_dash", "Dashboard"),
            destFor(HomeFragment::class, "navigation_home", "Home"),
            destFor(NotificationsFragment::class, "navigation_notifications", "Notifications"),
        )

        val graphBuilder = NavGraphBuilder(navController.navigatorProvider, dests[0].route!!, null)
        dests.forEach {
            graphBuilder.addDestination(it)
            navView.menu.add(Menu.NONE, it.id, Menu.NONE, it.label)
        }
        val graph = graphBuilder.build()

        navController.setGraph(graph, null)

        val appBarConfiguration = AppBarConfiguration(dests.map { it.id }.toSet())
        setupActionBarWithNavController(navController, appBarConfiguration)
        navView.setupWithNavController(navController)
    }
}