Kotlin Adapter Declaration issue: Type mismatch: inferred type is MyTabAdapter but RecyclerView.Adapter<(raw) RecyclerView.ViewHolder!>? was expected

Question

Making tabs with TabLayout and ViewPager2 and fragment. I am getting type mismatch on adapter. I am new to KOTLIN and Android if any suitable tutorial link is there which has implementation of tablayout with viewpager2

class ProfileActivity:AppCompatActivity() {
lateinit var toolbar: Toolbar
lateinit var tabLayout: TabLayout
lateinit var viewpager2: ViewPager2

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    setContentView(R.layout.activity_profile)

    // Toolbar

    toolbar=findViewById(R.id.toolbar)
    setSupportActionBar(toolbar)
    supportActionBar?.apply {
        title="Profile"

        // show back button on toolbar
        // on back button press, it will navigate to parent activity
        // mentioned in AndroidManifest.xml
        setDisplayHomeAsUpEnabled(true)
        setDisplayShowHomeEnabled(true)
    }

    // Tab layout - add tab items
    tabLayout=findViewById(R.id.profileTabLayout)
    tabLayout.addTab(tabLayout.newTab().setText("Personal"))
    tabLayout.addTab(tabLayout.newTab().setText("Education"))
    tabLayout.addTab(tabLayout.newTab().setText("Interests"))
    tabLayout.tabGravity=TabLayout.GRAVITY_FILL

    //Viewpager2
    viewpager2=findViewById(R.id.profileViewPager)

    //Adapter for view pager
    val adapter1=MyTabAdapter(this,supportFragmentManager,tabLayout.tabCount)

    viewpager2.adapter= adapter1

    viewpager2.addOnPageChangeListener(TabLayout.TabLayoutOnPageChangeListener(tabLayout))

    tabLayout.addOnTabSelectedListener(
        object : TabLayout.OnTabSelectedListener {

        override fun onTabSelected(tab: TabLayout.Tab) {
            viewpager2.currentItem = tab.position
        }
        override fun onTabUnselected(tab: TabLayout.Tab) {

        }
        override fun onTabReselected(tab: TabLayout.Tab) {

        }
    }
    )
}

}

Here is Code of MyAdapter Probably i am confused with FragmentStatePagerAdapter as it shows deprecated if there is any easy method to implement then i can try that also.

class MyTabAdapter(profileActivity: ProfileActivity, supportFragmentManager: FragmentManager, private var tabCount: Int) {


fun getItem(position: Int): Fragment? {

    when (position) {
        0 -> {
           // val homeFragment: HomeFragment = HomeFragment()
           // val personalFragment:PersonalFragment=PersonalFragment()
            return PersonalFragment()
        }
        1 -> {
            return EducationFragment()
        }
        2 -> {
            // val movieFragment = MovieFragment()
            return InterestsFragment()
        }
        else -> return null
    }

}
fun getCount(): Int {
    return tabCount
}

}

**Here is one of the fragment . I have three fragment in total.** I 

class PersonalFragment : Fragment() {
override fun onCreateView(
    inflater: LayoutInflater, container: ViewGroup?,
    savedInstanceState: Bundle?
): View? {
    // Inflate the layout for this fragment
    return inflater.inflate(R.layout.fragment_personal, container, false)
}

}

 I have referred the https://www.javatpoint.com/kotlin-android-tablayout-with-viewpager for implementation

I

Answer 1

There are two problems that I can see:

1. The article you were following used ViewPager but the snippet of codes that you attached showed that you were using ViewPager2.
2. MyTabAdapter extends nothing, it has to extend some kind of base adapter.

In your case, I suppose you wanted to use ViewPager2 to page through some fragments. You need to use FragmentStateAdapter.

Modify MyTabAdapter to be liked this

class MyTabAdapter(profileActivity: ProfileActivity, private val tabCount: Int) : FragmentStateAdapter(profileActivity) {

    override fun createFragment(position: Int): Fragment? {

        when (position) {
            0 -> {
                // val homeFragment: HomeFragment = HomeFragment()
                // val personalFragment:PersonalFragment=PersonalFragment()
                return PersonalFragment()
            }
            1 -> {
                return EducationFragment()
            }
            2 -> {
                // val movieFragment = MovieFragment()
                return InterestsFragment()
            }
            else -> return null
        }

    }
    
    override fun getItemCount(): Int {
        return tabCount
    }
}

Check here for detailed document of migrating from ViewPager to ViewPager2