Back from third to first fragment in android

Question

I have a problem with android fragment backstack. This is my situation.

// I can't post images yet, so I passed a link to it.

As you can see, I want to go from Fragment 1 to Fragment 2 and at the end to Fragment 3, but when I press back button at Fragment 3, I want to back to Fragment 1.

I do this like I describe on pic, but when I press Back Button nothing happen and when I press it second time, the app is closing.

My BackStack looks as expected, I have on it only "Main" entry. Also, when I add to backstack Fragment 2 I can back normally from Frag3 to Frag2 to Frag1 (but this is not what I want).

//Edit:

First:

I debug my app a little and I notice that when I press back button, Fragment is poped out from backstack and his lifecycle methods were invoked, but current fragment (Fragment 3) do nothing (I logged his onPause and onStop methods and they weren't invoked). Maybe this is a problem?

Second:

I found a solution that I implement onBackStackChange listener and in onBackStacChange method I simply replace Fragment3 with Fragment1. This works, but is it correct?

Answer 1

do it using....

FragmentManager fmManager = activity.getSupportFragmentManager();
if (fmManager.getBackStackEntryCount() > 0) { fmManager.popBackStack(fmManager.getBackStackEntryAt(fmManager.getBackStackEntryCount()-2).getId(), fmManager.POP_BACK_STACK_INCLUSIVE); } 

-2 is because you want to go two 2 fragment step back

Answer 2

@Override
public void onPageScrollStateChanged(int state) {
   int currentPage = mChannelPager.getCurrentItem();
   if (currentPage == mChannelsList.size() - 1 || currentPage == 0) {
          previousState = currentState;
          currentState = state;
          if (previousState == 1 && currentState == 0) {
              mChannelPager.setCurrentItem((currentPage == 0 ? mChannelsList.size() - 1 : 0), false);
            }
        }
     }
});

Write this code in your onPageChangeListner's onPageScrollStateChanged(int state)

Answer 3

1) Add First Fragment using below code

android.support.v4.app.FragmentManager fm = getActivity().getSupportFragmentManager();
        android.support.v4.app.FragmentTransaction ft=fm.beginTransaction();
        if (fm.findFragmentById(R.id.fragment_container) != null) {
            ft.hide(fm.findFragmentById(R.id.fragment_container));
        }
        ft.add(R.id.fragment_container, new OneFragment(),OneFragment.class.getCanonicalName())
                .addToBackStack(OneFragment.class.getCanonicalName()).commit();

2) Add Second Fragment From First fragment using below code

  android.support.v4.app.FragmentManager fm = getActivity().getSupportFragmentManager();
                    android.support.v4.app.FragmentTransaction ft=fm.beginTransaction();
                    if (fm.findFragmentById(R.id.fragment_container) != null) {
                        ft.hide(fm.findFragmentById(R.id.fragment_container));
                    }
                    ft.add(R.id.fragment_container,new TwoFragment(),TwoFragment.class.getCanonicalName())
.addToBackStack(TwoFragment.class.getCanonicalName()).commit();

3) Add Third Fragment From Second fragment using below code

android.support.v4.app.FragmentManager fm = getActivity().getSupportFragmentManager();
                android.support.v4.app.FragmentTransaction ft=fm.beginTransaction();
                if (fm.findFragmentById(R.id.fragment_container) != null) {
                    ft.hide(fm.findFragmentById(R.id.fragment_container));
                }
                ft.add(R.id.fragment_container, new ThreeFragment(),ThreeFragment.class.getCanonicalName())
                        .addToBackStack(ThreeFragment.class.getCanonicalName()).commit();

4) onBackPressed() please write below code

@Override
    public void onBackPressed() {
        hideKeyboard(MainActivity.this);
        Fragment currentFragment = this.getSupportFragmentManager().findFragmentById(R.id.fragment_container);

        if (currentFragment.getClass().getName().equalsIgnoreCase(ThreeFragment.class.getName())) { // Using this code come from third fragment to first fragment
            Fragment f = this.getSupportFragmentManager().findFragmentByTag(TwoFragment.class.getCanonicalName());
            if (f != null) {
                this.getSupportFragmentManager().popBackStackImmediate(f.getClass().getCanonicalName(), FragmentManager.POP_BACK_STACK_INCLUSIVE);
            }
        }else {
            super.onBackPressed();
        }
    }