Implementing proper back navigation and home button handling using Toolbar in Android

Question

I am using a single activity and multiple fragments(screenshot attached) within the same activity to provide a seamless navigation. But after implementing the latest toolbar and

Answer 1

Ok, after a lot of tests I finally succeeded to setup a good navigation. I needed exactly the same as you, the only difference is that I am using v4 Fragments, but I don't think this will change anything here.

I am not using ActionBarDrawerToggle since the latest examples from Google do not use this component anymore.

The solution below also works for deep navigation: parent activity --> fragment --> fragment etc.

The only change needed in the Fragments is to change the title:

@Override
public void onActivityCreated(Bundle savedInstanceState) {
    super.onActivityCreated(savedInstanceState);

    getActivity().setTitle(R.string.targets);
}

In the parent Activity onCreate method, I initialize the following:

    mNavigationView = (NavigationView) findViewById(R.id.navigation_view);
    setupDrawerContent(mNavigationView);

    final Toolbar toolbar = (Toolbar) findViewById(R.id.drawer_toolbar);
    setSupportActionBar(toolbar);

    getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_menu_24);// Set the hamburger icon
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);// Set home button pressable

    // Handle the changes on the actionbar
    getSupportFragmentManager().addOnBackStackChangedListener(
            new FragmentManager.OnBackStackChangedListener() {
                public void onBackStackChanged() {
                    // When no more fragments to remove, we display back the hamburger icon and the original activity title
                    if (getSupportFragmentManager().getBackStackEntryCount() <= 0) {
                        getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_menu_24);
                        setTitle(R.string.app_name);
                    }
                    // Else displays the back arrow
                    else {
                        getSupportActionBar().setHomeAsUpIndicator(R.drawable.ic_arrow_back_24);
                    }
                }
            });

Here is now the code to handle the action on the Home button:

@Override
public boolean onOptionsItemSelected(MenuItem item){
    // Close the soft keyboard right away
    Tools.setSoftKeyboardVisible(mViewPager, false);

    switch (item.getItemId()) {
        case android.R.id.home:

            // When no more fragments to remove, open the navigation drawer
            if (getSupportFragmentManager().getBackStackEntryCount() <= 0) {
                mDrawerLayout.openDrawer(GravityCompat.START);
            }
            // Removes the latest fragment
            else {
                getSupportFragmentManager().popBackStack();
            }

            return true;
    }
    return super.onOptionsItemSelected(item);
}

And finally the code to handle the back press action:

@Override
public void onBackPressed() {
    // When no more fragments to remove, closes the activity
    if (getSupportFragmentManager().getBackStackEntryCount() <= 0) {
        super.onBackPressed();
    }
    // Else removes the latest fragment
    else {
        getSupportFragmentManager().popBackStack();
    }
}

NOTE: I am using an AppCompatActivity, a NavigationView and the theme Theme.AppCompat.Light.NoActionBar.