Android: implementing two-way infinite viewing

Question

What I want:

I am trying to implement a bidirectional Endless viewpager on Android, left to right and right to left

What I've done:

I implemented the Endless adapterpager adapter , it works great for right-to-left direction, I set the current position of the position viewPager.setCurrentItem(Integer.MAX_VALUE/2);.

Reference:

Help will be appreciated.

Answer 1

Try checking below FragmentPagerAdapterto get endless viewpager adapter:

public static class MyAdapter extends FragmentPagerAdapter {
public MyAdapter(FragmentManager fm) {
    super(fm);
}

@Override
public int getCount() {
    return Integer.MAX_VALUE;
}

@Override
public Fragment getItem(int position) {
    return getFragmentBasedOnPosition(position);
}

private Fragment getFragmentBasedOnPosition(int position) {
    int fragmentPos = position % 3; // Assuming you have 3 fragments
    switch(fragmentPos) {
        case 0:
        return Fragment1.newInstance();
        case 1:
        return Fragment2.newInstance();
        case 2:
        return Fragment3.newInstance();
    }
 }
}

.

, .

Answer 2

, Integer.MAX_VALUE/2.

, , getCount Integer.MAX_VALUE .

, , :

onPageScrollStateChanged Listener

, viewPager , :

mainViewPager.addOnPageChangeListener(new ViewPager.OnPageChangeListener()
{
  Boolean first = false;
  Boolean last = false;

  @Override
  public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels)
  {}

  @Override
  public void onPageSelected(int position)
  {
    if (position == 0)
    {
      first = true;
      last = false;
    }
    else if (position == mainFragmentList.size() -1)
    {
      first = false;
      last = true;
    }
    else
    {
      first = false;
      last = false;
    }
  }

  @Override
  public void onPageScrollStateChanged(int state)
  {
    if (first && state == ViewPager.SCROLL_STATE_IDLE)
    {
      // Jump without animation
      Fragment fragment = mainFragmentList.get(mainFragmentList.size() -1);
      mainFragmentList.remove(mainFragmentList.size() -1 );
      mainFragmentList.add(0,fragment);
      mainPagerAdapter.setData(mainFragmentList);
      mainPagerAdapter.notifyDataSetChanged();
      Log.e(TAG,mainFragmentList.toString());
      mainViewPager.setCurrentItem(1,false);
    }
    if(last && state == ViewPager.SCROLL_STATE_IDLE)
    {
      // Jump without animation
      Fragment fragment = mainFragmentList.get(0);
      mainFragmentList.remove(0);
      mainFragmentList.add(fragment);
      mainPagerAdapter.setData(mainFragmentList);
      mainPagerAdapter.notifyDataSetChanged();
      Log.e(TAG,mainFragmentList.toString());
      mainViewPager.setCurrentItem(mainFragmentList.size()-2,false);
    }
  }
});

: 4 A-B-C-D A (), : D-A-B-C [ ] ViewPager ( ) A, 1. D.

: A-B-C-D D (), : B-C-D-A [ ] ViewPager ( ) D, mainFragmentList.size() -2. .

FragmentStatePagerAdapter, FragmentPagerAdapter