Fragment addToBackStack behaviour

Question

I'm facing two problems with fragments in Android.

I have an app with a Navigation Drawer Fragment inside my MainActivity. When I click in an item on this Navigation Drawer, a new fragment is load on the "fragment_placeholder" inside the Main Activity. Pretty simple.

When the MainActivity is created, I'm loading "homeFragment" inside fragment_placeholder. This fragment has a SlidingTabLayout with two tabs, each one loading it´s corresponding fragment. This Home Fragment is my "main" part of the app.

When I click on another item in Navigation Drawer, the Home Fragment is replaced with the another Fragment, for example, when I click on "My account", the "My account fragment" is loaded on fragment_placeholder. I have 3 itens in the Navigation Drawer.

I want to keep the Home Fragment (and the two tabs/fragments inside it) on back stack, so I can navigate on any fragment (my account, config, and so on) and when I press back button, I'm getting back to Home Fragment.

I tried to addToBackStack the Home Fragment inside onCreate of MainActivity (before I commit it), but is not working properly. If I press the "My account" item on navigation drawer, and then press back, the app load "My account" fragment again, and if I press back again, app is closed. Another case: if I press the "Home" item, and then press back, the app back to the same home fragment but without any tab (it´s not loading the two fragments belonging to him).

Here is my app:

MainActivity

Here is my code: MainActivity

public class MainActivity extends ActionBarActivity {

private Toolbar mToolbar;

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

    // Loading home fragment
    if (findViewById(R.id.fragment_placeholder) != null) {

        if (savedInstanceState != null) {
            return;
        }
        FragmentTransaction fragmentTransaction = getSupportFragmentManager().beginTransaction();
        HomeFragment homeFragment = new HomeFragment();
        homeFragment.setArguments(getIntent().getExtras());

        fragmentTransaction.replace(R.id.fragment_placeholder, homeFragment);
        fragmentTransaction.addToBackStack(null); // This is not working properly
        fragmentTransaction.commit();
    }
}

Navigation Drawer: itemClicked method

 @Override
public void itemClicked(View view, int position) {

    FragmentTransaction fragmentTransaction = fragmentManager.beginTransaction();

    switch(position)
    {
        // Home
        case 0:
            HomeFragment homeFragment = new HomeFragment();
            fragmentTransaction.replace(R.id.fragment_placeholder, homeFragment);
            break;

        // My account
        case 1:
            MyAccountFragment myAccountFragment = new MyAccountFragment();
            fragmentTransaction.replace(R.id.fragment_placeholder, myAccountFragment);
            break;

        // Config
        case 2:
            ConfigFragment configFragment = new ConfigFragment();
            fragmentTransaction.replace(R.id.fragment_placeholder, configFragment );
            break;

    }

    fragmentTransaction.commit();
    mDrawerLayout.closeDrawer(mDrawerListView);


}

Thank you and sorry about my english.

score 0 · Accepted Answer · edited May 23 '17 at 12:14

I found a solution, based on this answer https://stackoverflow.com/a/14588642/1959257

I changed my code to:

public void onBackPressed() {
    HomeFragment homeFragment = new HomeFragment();
    displayFragment(homeFragment);
}

 private void displayFragment(Fragment pFragment) {

   // Fragment currently inside the placeholder view
   Fragment fr = (Fragment) getSupportFragmentManager()
            .findFragmentById(R.id.fragment_placeholder);

   // If this fragment is a HomeFragment, close app
   if (fr instanceof HomeFragment) {
        finish();
   }
   else {
        // Replace curretly Fragment by HomeFragment
        FragmentTransaction ft = getSupportFragmentManager().beginTransaction();
        ft.replace(R.id.fragment_placeholder, pFragment);
        ft.commit();
   }
}

Fragment addToBackStack behaviour

1 Answers1