ActionBar Home button - hide fragment and clear back stack

Question

I would like to implement Home/Up button in the actionBar. I have simple application with one Activity (A) and two fragments (Settings (B) and About (C)).

In the other questions I have found to use popBackStack, but that's not the solution bacause if user goes A > B > C > B > C, back-button goes C > B > C > B > A (is this correct behaviour?).

    switch (item.getItemId()){
        case R.id.action_settings:
            // get preferences fragment
            getFragmentManager().beginTransaction()
                    .replace(android.R.id.content, new PrefFragment())
                    .addToBackStack(null)
                    .commit();
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            return true;
        case R.id.action_about:
            // get about fragment
            getFragmentManager().beginTransaction()
                    .replace(android.R.id.content, new AboutFragment())
                    .addToBackStack(null)
                    .commit();
            getSupportActionBar().setDisplayHomeAsUpEnabled(true);
            return true;
        case android.R.id.home:
            // clear back stack and show home screen?

            getSupportActionBar().setDisplayHomeAsUpEnabled(false);
            return true;
    }

I would need last case to hide any fragment (show main activity window) and clear my back stack - go home, not back. How could I achieve that?

I use AppCompat library.

Answer 1

try this:

 private void clearBackStack() {
    FragmentManager manager = getSupportFragmentManager();
    if (manager.getBackStackEntryCount() > 0) {
        FragmentManager.BackStackEntry first = manager.getBackStackEntryAt(0);
         manager.popBackStack(first.getId(), FragmentManager.POP_BACK_STACK_INCLUSIVE);
    }
}

or call

mFragmentManager.popBackStack(null, FragmentManager.POP_BACK_STACK_INCLUSIVE); 

Form the documentation POP_BACK_STACK_INCLUSIVE is

Flag for popBackStack(String, int) and popBackStack(int, int): If set, and the name or ID of a back stack entry has been supplied, then all matching entries will be consumed until one that doesn't match is found or the bottom of the stack is reached.