Как открывать layout файлы в BottomNavigationView?

Как с помощью BottomNavigationView реализовать открытие определенных layout xml? Вот код, который реализует вывод текста, а как реализовать открытие layout'?

public class MainActivity extends AppCompatActivity {
    private TextView textFavorites;
    private TextView textCollection;
    private TextView textFriends;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        textFavorites = (TextView) findViewById(R.id.text_favorites);
        textCollection = (TextView) findViewById(R.id.text_collection);
        textFriends = (TextView) findViewById(R.id.text_friends);
        BottomNavigationView bnv = (BottomNavigationView) findViewById(R.id.bottom_navigation);
        bnv.setOnNavigationItemSelectedListener(getBottomNavigationListener());
    }
    @NonNull
    private BottomNavigationView.OnNavigationItemSelectedListener getBottomNavigationListener() {
        return new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                switch (item.getItemId()) {
                    case R.id.action_favorite:
                        textFavorites.setVisibility(View.VISIBLE);
                        textCollection.setVisibility(View.GONE);
                        textFriends.setVisibility(View.GONE);
                        break;
                    case R.id.action_collection:
                        textFavorites.setVisibility(View.GONE);
                        textCollection.setVisibility(View.VISIBLE);
                        textFriends.setVisibility(View.GONE);
                        break;
                    case R.id.action_friends:
                        textFavorites.setVisibility(View.GONE);
                        textCollection.setVisibility(View.GONE);
                        textFriends.setVisibility(View.VISIBLE);
                        break;
                }
                return true;
            }
        };
    }
}

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.content.Intent;
import android.support.annotation.NonNull;
import android.support.design.widget.BottomNavigationView;
import android.app.Fragment;
import android.view.MenuItem;


public class MainActivity extends AppCompatActivity {


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


        BottomNavigationView bnv = (BottomNavigationView) findViewById(R.id.bottom_navigation);
        bnv.setOnNavigationItemSelectedListener(getBottomNavigationListener());
    }
    @NonNull
    private BottomNavigationView.OnNavigationItemSelectedListener getBottomNavigationListener() {
        return new BottomNavigationView.OnNavigationItemSelectedListener() {
            @Override
            public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                switch (item.getItemId()) {
                    case R.id.action_zametki:
                        changeFragment(R.layout.main);
                        return true;
                    case R.id.action_spisok:
                        changeFragment(R.layout.spisok_activity);
                        return true;
                    case R.id.action_cal:
                        changeFragment(R.layout.cal_activity);
                }
                return false;
            }
            public void changeFragment(Fragment fragment) {
                getFragmentManager().beginTransaction()
                        .replace(R.id.fragmentContainer, fragment) // id  FrameLayout
                        .commit();
            }
            };
        }
    }