ViewPager returning wrong fragment

Question

I want to use ViewPager to swipe through songs in my Media Player ( going forward or backward like SoundCloud app for android ). I have created a fragment which I inflate and set inside information like song name, author etc.

I have read some topics on StackOverflow about the ViewPager displays wrong items ( Viewpager shows wrong page and Android Viewpager show wrong pages and a lot more ) but I don't have fixed number of XML's to use with the ViewPager.

My Data is displayed in a RecyclerView, when I am pressing the item on index 4 for example I call the following method:

       mPager.setCurrentItem(position);

So the mPager is set to position 4.

    @Override
    public Fragment getItem(int position) {
        Log.i("TEST","Returnin a fragment on position "+position);
        return fragment = new MusicSliderFragment();
    }

But on my Adapter when it's changing I get the following output:

02-23 10:39:57.131 7599-7599/************** I/TEST: Returning a fragment on position 4
02-23 10:39:57.131 7599-7599/************** I/TEST: Returning a fragment on position 3
02-23 10:39:57.131 7599-7599/************** I/TEST: Returning a fragment on position 5

And when my application is launched I get the following output:

I/TEST: Returning a fragment on position 0
I/TEST: Returning a fragment on position 1

The main problem is when I am opening the app first time and set the song on position 4 the fragment information are displayed in the next fragment.

Is there a way how can I fix this?

Adapter Class:

 private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {

        private MusicSliderFragment fragment;

        public ScreenSlidePagerAdapter(FragmentManager fm) {
            super(fm);
        }

        @Override
        public Fragment getItem(int position) {
            Log.i("TEST","Returnin a fragment on position "+position);
            return fragment = new MusicSliderFragment();
        }

        @Override
        public int getCount() {
            return NUM_PAGES;
        }

        public void updateSongName(String name) {
            fragment.setSongName(name);
        }
    }

The RecyclerView Listener :

            musicList.addOnItemTouchListener(
            new RecyclerItemClickListener(getApplicationContext(), new RecyclerItemClickListener.OnItemClickListener() {
                @Override
                public void onItemClick(View view, final int position) {

                        Log.i("TEST", "Setting the mPager position to: "+position);
                        mPager.setCurrentItem(position);
                    }
                }


And the `Listener` of the `mPager` where I update the song name for example:

mPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {

                play(position);

                ScreenSlidePagerAdapter adapter = (ScreenSlidePagerAdapter) mPager.getAdapter();
                adapter.updateSongName(splitName(myDataList.get(position))[0]);

                Log.i("TEST", "Playing the position: "+position);
                mPagerAdapter.notifyDataSetChanged();
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });

Do you mean position four is fourth fragment? Does your index start from 0 or 1? — Murali krishna, Feb 23 '16 at 09:23
My position in Arrays and RecyclerView starts from 0, about the position of viewpager I think it starts from 0. — Marian Pavel, Feb 23 '16 at 09:35
No it starts from 0 just set the position as 3 it should work for you.Let me know if that is the problem. — Murali krishna, Feb 23 '16 at 09:37

score 2 · Answer 1 · answered Feb 23 '16 at 09:15

2

View pager can load neighbour fragments when you choose current. Method setOffscreenPageLimit() defines how many neighbours you want to preload. onPageSelected(int position) should work correct and returns current item.

answered Feb 23 '16 at 09:15

Konstantin Volkov

300
1
9

So the viewpager load the page 4 and then load the neighbour ( 3 and 5 ), how can I make it return the fragment 4 then :) ? – Marian Pavel Feb 23 '16 at 09:17
if you want to reach fragment 4 you can swipe one by one. Or if you whant reach it immediately you can pager.setCurrentItem( num ). – Konstantin Volkov Feb 23 '16 at 09:25
I am doing that in RecyclerView listner, but then how you said, it's getting it's neighbour 3 and 5 and the current fragment remains 5. – Marian Pavel Feb 23 '16 at 09:34

score 0 · Answer 2 · answered Feb 23 '16 at 09:44

0

Viewpager indexing starts from zero if you want to load the fourth Fragment then you need to set the position 3.

  mPager.setCurrentItem(3); //Load the 4th fragment according to you.(0-3)

answered Feb 23 '16 at 09:44

Murali krishna

823
1
8
23

My recyclerview starts from 0 too, so when I am loading the index 4 the mPager set the index to 4, I don't think this is the problem, if I do the position - 1 trick when I am pressing the index 0 from RecyclerView it will call the setCurrentItem to -1 and that is not correct. – Marian Pavel Feb 23 '16 at 09:49

ViewPager returning wrong fragment

2 Answers2