Replaced fragment still visible

Question

When I start my app it runs an AsyncTask to load up and then in onPostExecute, I then setContentView to the new layout then add a fragment with two buttons offering two modes by an add FragmentTransaction. After one of the two modes is clicked, it then replaces the fragment with yet another FragmentTransaction using the replace method.

If the app crashes it returns to the first screen, loading up the two buttons offering the two modes. In this case if either mode is selected, the second fragment is loaded but is now the background is suddenly transparent showing the two buttons below and they remain clickable. If they are clicked again they properly replace the fragment so that it isn't visible below. This is just weird, I can't understand what could cause this.

I've researched and seen these two similar questions, one and two, which suggested that it might be because the ID is wrong or I have defined the fragment in XML. Neither of these two factors are the case.

My code is shown below:

Below I replace the loading screen.

@Override
    protected void onPostExecute(Void result) {
        setContentView(R.layout.activity_main_screen);
        FragmentTransaction transaction = getSupportFragmentManager()
                .beginTransaction();
        transaction.add(R.id.fragment_container, new ModeFragment())
                .commit();
            }

After which, when a button is clicked I pass the fragment I wish to replace the current with into this method below:

private void replaceCurrentFragment(Fragment fragment) {
    FragmentTransaction transaction = getSupportFragmentManager()
            .beginTransaction();
    transaction.replace(R.id.fragment_container, fragment)
            .setTransition(FragmentTransaction.TRANSIT_FRAGMENT_OPEN)
            .addToBackStack(null).commit();
}

This works the first time, however if a crash occurs then the app returns to the first fragment and the second time this method is passed, the new replacing fragment is semi-invisible. Clicking the button on the first fragment again calls this method again and it is now fine.

Obviously I don't want the app to crash so this shouldn't occur, but I get this feeling that there's something wrong with how I'm writing my code.

Answer 1

I've had the same problem happen to me, and it was because I loaded a fragment in the OnCreate of my Activity, without checking if there was a savedInstanceState, so android first reopen all old fragments, then do the OnCreate, which added the fragment over the old ones without replacing them so when you navigate to another fragment, it only replaces the top one, but not the bottom one, so you will see the fragments under it.

Might not be exactly the same thing for you, but it might help you figure it out.