Viewpager in Android to switch between days endlessly

Question

I am currently making a app where students can view there lesson grid. The lessons are retrieved using a json file. Now the date changing is done via buttons in the actionbar, but i want to make it also work with smooth swipe effects.

The only things that need to change is the SlectedDate-1 on left swipe. the SelectedDate+1 on right swipe.

I tried it with ViewPagers but it didn't work does anybody know how to do it? Maybe something with 3 viewpagers?, please a detailed code because I'm not very familar with viewpagers code!

I've tried out Android ViewPager working with date code but it doesn't work for me.

 private class ScreenSlidePagerAdapter extends FragmentStatePagerAdapter {
    public ScreenSlidePagerAdapter(FragmentManager fm) {
        super(fm);
    }

    @Override
    public Fragment getItem(int position) {
        String myFormat = "yyyy-MM-dd"; 
        SimpleDateFormat sdf = new SimpleDateFormat(myFormat, Locale.US);

         switch (position) {
           case 0:
                  // create your dates for the leftmost fragment  
                    myCalendar.add(Calendar.DAY_OF_YEAR, -1);
                    final String dateje = sdf.format(myCalendar.getTime());
                   // mPager.setCurrentItem(1);
                  return ScreenSlidePageFragment.create(dateje);


              case 1:
                  // create your dates for the center fragment 
                  myCalendar.add(Calendar.DAY_OF_YEAR, 0);
                final String dateje2 = sdf.format(myCalendar.getTime());
              //mPager.setCurrentItem(1);
              return ScreenSlidePageFragment.create(dateje2);

              case 2: 
                  myCalendar.add(Calendar.DAY_OF_YEAR, 1);
                final String dateje3 = sdf.format(myCalendar.getTime());
              //mPager.setCurrentItem(1);

              return ScreenSlidePageFragment.create(dateje3);
           }

      return null;
    }

    @Override
    public int getCount() {
        return 3;
    }

my example fragment

public class ScreenSlidePageFragment extends Fragment {
    /**
     * The argument key for the page number this fragment represents.
     */
    public static final String ARG_PAGE = "page";

    /**
     * The fragment's page number, which is set to the argument value for {@link #ARG_PAGE}.
     */
    private int mPageNumber;

    /**
     * Factory method for this fragment class. Constructs a new fragment for the given page number.
     */
    public static ScreenSlidePageFragment create(String dateNumber) {
        ScreenSlidePageFragment fragment = new ScreenSlidePageFragment();
        Bundle args = new Bundle();
        args.putString(ARG_PAGE, dateNumber);
        fragment.setArguments(args);
        return fragment;
    }

    public ScreenSlidePageFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        mPageNumber = 1;



    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState) {
        // Inflate the layout containing a title and body text.
        ViewGroup rootView = (ViewGroup) inflater
                .inflate(R.layout.fragment_screen_slide_page, container, false);


        String date = this.getArguments().getString(ARG_PAGE);
        // Set the title view to show the page number.
        ((TextView) rootView.findViewById(android.R.id.text1)).setText(date);

        return rootView;
    }

    /**
     * Returns the page number represented by this fragment object.
     */
    public int getPageNumber() {
        return mPageNumber;
    }
}

Answer 1

I have fixed this problems a little time ago, this code is a bit based on the answer from Kuffs but I don't get the date in an array because it's a lot of performance to put a lot of days in array.

Summary of code (1) The code makes a FragmentPager with around 10.000 pages in it. On the main activity init the app set the current page to the middle(5000).

pager.setAdapter(new BootstrapPagerAdapter(getResources(), getSupportFragmentManager()));
pager.setCurrentItem(5000, false);
pager.post(new Runnable() {
    public void run() {
        pager.setCurrentItem(5000, false);
    }
});
pager.getAdapter().notifyDataSetChanged();
pager.setOffscreenPageLimit(0);

Summary of code (2) in the bootstrappageradapter

The code looks what position the user has scrolled and looks for the date now

DateTime pagerdate = DateTime.now(TimeZone.getDefault());
DateTime days = pagerdate.plusDays(position - 5000);

e.g. user swiped three days next. position is 5003, so the sum is 5003-5000=3 days

The days count easily plus 3 days with date4j library (I highly recommend it!) then I make a new fragment with the date in its bundle!

public class BootstrapPagerAdapter extends FragmentPagerAdapter
{
    /**
    * Create pager adapter
    *
    * @param resources
    * @param fragmentManager
    */
    public BootstrapPagerAdapter(Resources resources, FragmentManager fragmentManager) {
        super(fragmentManager);
    }

    @Override
    public int getCount() {
        return 10000;
    }

    @Override
    public int getItemPosition(Object object){
        return FragmentStatePagerAdapter.POSITION_NONE;
    }

    @Override
    public Fragment getItem(int position) {
        DateTime pagerdate = DateTime.now(TimeZone.getDefault());
        DateTime days = pagerdate.plusDays(position - 5000);

        Bundle bundle = new Bundle();
        bundle.putString("date", days.format("YYYY-MM-DD").toString());

        RoosterFragment roosterFragment = new RoosterFragment();
        roosterFragment.setArguments(bundle);

        return roosterFragment;
    }
}

You could fake the endlessly count with more high numbers like

• year 0001
• year 3999

Around the: 1.500.000 days believe me no one is gonna go this far all the way swiping!

I've tried the a lot infinite examples but this is the only working example I think!

Upvote if it worked for you and don't be shy to ask for more examples or help with your app!

However it would be cool if someone got something like a really infinte viewpager without fake counts and so on ;)