Using Android navigation component with single activiy, layout drawer and toolbars inside fragments

Question

Is it possible to use Android Navigation component/graph in the single activity app in which each fragment has its own toolbar?

Also, container activity has a navigation drawer that needs setup with toolbar and navigation controller, but at the time of activity creation I don't have yet the toolbar.

I am using this code (called in onCreate)

    private fun setupNavigation() {

//        val toolbar = findViewById<Toolbar>(R.id.toolbar);
//        setSupportActionBar(toolbar);
//        supportActionBar!!.setDisplayHomeAsUpEnabled(true);
//        supportActionBar!!.setDisplayShowHomeEnabled(true);

    val drawerLayout = findViewById<DrawerLayout>(R.id.drawer_layout);

    val navigationView = findViewById<NavigationView>(R.id.drawer_navigation_view);

    val navController = Navigation.findNavController(this, R.id.navigation_host_fragment);

    NavigationUI.setupActionBarWithNavController(this, navController, drawerLayout)

    NavigationUI.setupWithNavController(navigationView, navController)

    navigationView.setNavigationItemSelectedListener(this)
}

But since I don't have toolbar at the time it throws an error (ActionBar.setTitle called on a null object).

Is it possible to have this, or I need to drop the idea to use navigation component in this case?

Answer 1

The only requirement is that you call setupActionBarWithNavController after you call setSupportActionBar(). If you're doing that in your Fragment, then just call setupActionBarWithNavController directly after that.

For example, in your Fragment:

private fun onViewCreated(view: View, bundle: savedInstanceState) {

  val toolbar = view.findViewById<Toolbar>(R.id.toolbar);
  // Set the Toolbar as your activity's ActionBar
  requireActivity().setSupportActionBar(toolbar);

  // Find the activity's DrawerLayout
  val drawerLayout = requireActivity().findViewById<DrawerLayout>(R.id.drawer_layout);

  // Find this Fragment's NavController
  val navController = NavHostFragment.findNavController(this);

  // And set up the ActionBar
  NavigationUI.setupActionBarWithNavController(this, navController, drawerLayout)
}

There's also a separate NavigationUI.setupWithNavController() method that takes a Toolbar. This would be appropriate if you aren't actually using any of the other ActionBar APIs.