Migration from ViewPager to ViewPager2

Capabilities:

• Support Verticle Scroll
• Page Change Callback [onPageScrolled(), onPageSelected(), onPageScrollStateChanged()]
• Support Right-to-left tabs order
• Combined with the DiffUtil and other features backed by the recycler view (animations etc)

Changes Required for migration ViewPager -> ViewPager2

1. Adapter parant class

from: class MyAdapter : PagerAdapter()

to: class MyAdapter : RecyclerView.Adapter<>()

// If using ViewPager with fragments

from: class MyFragmentAdapter( fm: FragmentManager ) : FragentStatePagerAdapter(fm, ...)

to: class MyFragmentAdapter( fa: FragmentActivity // or f: Fragment // or fm: FragmentManager, l: Lifecycle ) : FragentStateAdapter(fa, ...)

2. To get the count

from: override fun getCount(): Int {...}

to: override fun getItemCount(): Int {...}

3. To get Item

from: override fun getItem(postion: Int): Framgent {...}

to: override fun createFragment(postion: Int): Fragment {...}

To use tab layout with ViewPager2

1. Tablayout decoupled from ViewPager2 and available in Material Components. So it is required to implement Material Desing library
2. Changes required in the fragment

from: tabLayout.setupWithViewPager(viewPager);

to: TabLayouMediator (tablayout, viewpager){tab, postion -> // here we can modify the tabs tabs.text = "Item ${(position + 1)}" }.attach()