How can I switch between Fragments without destroying them?

I'm playing with native Android apps navigation, using BottomNavigationBar to switch between Fragments:

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        // ...
    }

    private BottomNavigationView.OnNavigationItemSelectedListener navListener =
            new BottomNavigationView.OnNavigationItemSelectedListener() {
                @Override
                public boolean onNavigationItemSelected(@NonNull MenuItem item) {
                    Fragment selectedFragment = null;

                    switch (item.getItemId()) {
                        case R.id.first:
                            selectedFragment = new FirstFragment();
                            break;
                        case R.id.second:
                            selectedFragment = new SecondFragment();
                            break;
                        case R.id.third:
                            selectedFragment = new ThirdFragment();
                            break;
                    }

                    getSupportFragmentManager()
                        .beginTransaction()
                        .replace(R.id.container, selectedFragment)
                        .commit();

                    return true;

                }
            };
}

I want those Fragments to persist between navigations. Any suggestions?

Here's the best solution I could find:

• First of all, all of the Fragments are declared as fields inside MainActivity:

private SecondFragment second_fragment = new SecondFragment();
private FirstFragment first_fragment = new FirstFragment();
private ThirdFragment tird_fragment = new ThirdFragment();
    
Fragment selected = second_fragment;`

• Then, the following methods are defined:

private void createFragment(Fragment fragment){
    getSupportFragmentManager()
        .beginTransaction()
        .add(R.id.container, fragment)
        .hide(fragment)
        .commit();
}
private void showFragment(Fragment fragment){
    getSupportFragmentManager()
        .beginTransaction()
        .show(fragment)
        .commit();
}
private void hideFragment(Fragment fragment){
    getSupportFragmentManager()
        .beginTransaction()
        .hide(fragment)
        .commit();
}

• Finally, this method puts it all together:

private BottomNavigationView.OnNavigationItemSelectedListener navListener =
    new BottomNavigationView.OnNavigationItemSelectedListener() {
        @Override
        public boolean onNavigationItemSelected(@NonNull MenuItem item) {
            hideFragment(selected);

            switch (item.getItemId()) {
                case R.id.first:
                    selected = first_fragment;
                    break;
                case R.id.second:
                    selected = second_fragment;
                    break;
                case R.id.third:
                    selected = third_fragment;
                    break;
            }
            
            showFragment(selected);

            return true;
    }
};

This way the menu just hides and shows Fragments visually.