public class MainActivity extends AppCompatActivity {
    protected BottomNavigationView bottomNavigationView;
    protected FrameLayout frameLayout;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        frameLayout = (FrameLayout) findViewById(R.id.content_frame);
        bottomNavigationView = (BottomNavigationView) findViewById(R.id.bottom_navigation);
        bottomNavigationView.setOnNavigationItemSelectedListener(
                new BottomNavigationView.OnNavigationItemSelectedListener() {
                    @Override
                    public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                        switch (item.getItemId()) {
                            case R.id.action_subscribed:
                                startActivity(new Intent(getApplicationContext(), SubscribedShowsActivity.class));
                                break;
                            case R.id.action_search:
                                startActivity(new Intent(getApplicationContext(), SearchActivity.class));
                                break;
                            case R.id.action_upcoming:
                                startActivity(new Intent(getApplicationContext(), UpcomingEpisodesActivity.class));;
                                break;
                        }
                        return true;
                    }
                });
    }

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <FrameLayout
        android:layout_height="match_parent"
        android:layout_width="match_parent"
        android:id="@+id/content_frame"/>

    <android.support.design.widget.BottomNavigationView
        android:id="@+id/bottom_navigation"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        app:itemBackground="@color/colorPrimary"
        app:itemIconTint="@drawable/nav_item_color_state"
        app:itemTextColor="@drawable/nav_item_color_state"
        app:menu="@menu/bottom_navigation_main" />

</RelativeLayout>

public class SubscribedShowsActivity extends MainActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        LayoutInflater inflater = (LayoutInflater) this
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View contentView = inflater.inflate(R.layout.activity_upcoming_episodes, null, false);
        bottomNavigationView.addView(contentView, 0);

        if (savedInstanceState == null) {
            getSupportFragmentManager().beginTransaction()
                    .add(R.id.content_frame, new SubscribedShowsFragment())
                    .commit();
        }
    }
}

@Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        LayoutInflater inflater = (LayoutInflater) this
                .getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        View contentView = inflater.inflate(R.layout.activity_search, null, false);
        bottomNavigationView.addView(contentView, 0);