After first fragment replaced by the second, How to open the navigation drawer

Question

I have created the default Android Studio Navigation Drawer project. By default, I have one activity and three main fragments. (Home, Gallery, Slideshow), I am only trying with the Home Fragment. I have replaced the < fragment > from the content_main XML to

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

and Modified the MainActivity as

//inside onCreate
NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.nav_host_fragment_content_main);

    NavController navController;
    if (navHostFragment != null) {
        navController = navHostFragment.getNavController();
        NavigationUI.setupActionBarWithNavController(this, navController, mAppBarConfiguration);
        NavigationUI.setupWithNavController(navigationView, navController);
    } else {
        Log.e("Error", "Failed on NULL NavController");
    }

//and modified the following

@Override
public boolean onSupportNavigateUp() {
    NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.nav_host_fragment_content_main);
    assert navHostFragment != null;
    return NavigationUI.navigateUp(navHostFragment.getNavController(), mAppBarConfiguration)
            || super.onSupportNavigateUp();
}

Next, I have created one BlankFragment. On the home Fragment, I have a button and onClickListener to replace the HomeFragment with BlankFragment as

binding.button.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {
            Log.d("onClick: ", "Clicked");
            BlankFragment blankFragment = new BlankFragment();
            requireActivity().getSupportFragmentManager().beginTransaction()
                    .replace(R.id.nav_host_fragment_content_main, blankFragment, null)
                    .addToBackStack("blank").commit();
        }
    });

Now after clicking on the button the fragment is replaced with the blank fragment but from there if I try to open the Navigation drawer I get the following Error for the first line of the above onSupportNavigateUp() function :

java.lang.ClassCastException: BlankFragment cannot be cast to androidx.navigation.fragment.NavHostFragment

How to solve this. Thanks in Advance.

Answer 1

As suggested by Zain in the comment, I tried using navController. Tried the following and it seems to work, posting for others. https://learntodroid.com/how-to-move-between-fragments-using-the-navigation-component/