How to add ViewModel to a project which uses ViewPager and Tablayout?

Question

Hello i am new in Android Development so maybe this question can be weird for you.

I have a class named IdentityCardInfo which has variables. And I am getting this variables in InfoFragment.

From InfoFragment I want to show these variables in a ResultsFragment wihch has 3 tabs with tablayout.

I want to use ViewModel to pass data to tablayouts but I don't know how to use I've searched but get stuck.

Here is code for IdentityCardInfo class:

class IdentityCardInfo {

    companion object AppConstant{
        const val serieNo ="67G74444"
        const val validDate = "01/01/2022"
        const val dateOfBirth = "10/08/1998"
        const val fullName = "Muhittin KAYA"
        const val identityNo: Long = 11111111111
        const val gender = "MALE"
        const val nationality = "TUR"
    }
}

Here is code for InfoFragment:

class InfoFragment : BaseFragment() {

    lateinit var navController: NavController

    companion object {
        private const val TAG = "Info Fragment"
    }

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

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        navController = Navigation.findNavController(view)
        button_info_idcard.setOnClickListener {
            //start OcrActivity
            val intent = Intent(activity, OcrActivity::class.java)
            startActivityForResult(intent, 101)
        }

        imagebutton_info_settings.setOnClickListener {
            navController.navigate(R.id.action_infoFragment_to_settingsFragment)
        }
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        Log.i("Muhittin", "onActivityResult()")

        if (requestCode == 101) {
            val message = data?.getStringExtra("TEST_TEXT")
            Toast.makeText(context, message, Toast.LENGTH_SHORT).show()

            val serieNo = IdentityCardInfo.serieNo
            val validDate = IdentityCardInfo.validDate
            val dateOfBirth = IdentityCardInfo.dateOfBirth
            val fullname = IdentityCardInfo.fullName
            val gender = IdentityCardInfo.gender
            val identityNo = IdentityCardInfo.identityNo
            val nationality = IdentityCardInfo.nationality

            val bundle = bundleOf(
                "TEST_TEXT" to message,
                "SERIE_NO" to serieNo,
                "VALID_DATE" to validDate,
                "DOB" to dateOfBirth,
                "FULL_NAME" to fullname,
                "GENDER" to gender,
                "IDENTITY_NO" to identityNo,
                "NATIONALITY" to nationality
            )
            navController.navigate(
                R.id.action_infoFragment_to_detailFragment,
                bundle
            )
        }
    }
}

This is for ResultsFragment: (I don't add tablayout code and viewpager code)

class ResultsFragment : Fragment() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        retainInstance = true
    }

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

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        val tabLayout: TabLayout = requireView().findViewById(R.id.tabLayout_results)

        tabLayout.tabGravity = TabLayout.GRAVITY_FILL
        val tabTitles = arrayOf(
            resources.getString(R.string.result_tab1_name),
            resources.getString(R.string.result_tab2_name),
            resources.getString(R.string.result_tab3_name)
        )

        val viewPager: ViewPager = requireView().findViewById(R.id.viewpager_results)
        viewPager.offscreenPageLimit = 3
        val adapter = PagerAdapter(fragmentManager, tabTitles)
        viewPager.adapter = adapter
        tabLayout.setupWithViewPager(viewPager)
    }

}

Answer 1

@muhittin kaya Refer below code to resolve your issue

InfoFragment

class InfoFragment : BaseFragment() {

    lateinit var navController: NavController

    // Initialize your variable
    lateinit var infoFragmentInterface: InfoFragmentDataInterface

    // If you get initialization exception then uncomment below line and comment above line
    //private var  infoFragmentInterface: InfoFragmentDataInterface? = null


    companion object {
        private const val TAG = "Info Fragment"
    }

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

    override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)
        navController = Navigation.findNavController(view)
        button_info_idcard.setOnClickListener {
            //start OcrActivity
            val intent = Intent(activity, OcrActivity::class.java)
            startActivityForResult(intent, 101)
        }

        imagebutton_info_settings.setOnClickListener {
            navController.navigate(R.id.action_infoFragment_to_settingsFragment)
        }
    }

    override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
        super.onActivityResult(requestCode, resultCode, data)
        Log.i("Muhittin", "onActivityResult()")

        if (requestCode == 101) {
            val message = data?.getStringExtra("TEST_TEXT")
            Toast.makeText(context, message, Toast.LENGTH_SHORT).show()

            val serieNo = IdentityCardInfo.serieNo
            val validDate = IdentityCardInfo.validDate
            val dateOfBirth = IdentityCardInfo.dateOfBirth
            val fullname = IdentityCardInfo.fullName
            val gender = IdentityCardInfo.gender
            val identityNo = IdentityCardInfo.identityNo
            val nationality = IdentityCardInfo.nationality

            val bundle = bundleOf(
                "TEST_TEXT" to message,
                "SERIE_NO" to serieNo,
                "VALID_DATE" to validDate,
                "DOB" to dateOfBirth,
                "FULL_NAME" to fullname,
                "GENDER" to gender,
                "IDENTITY_NO" to identityNo,
                "NATIONALITY" to nationality
            )

            //Add This line for passing your data
            //You can also pass string data here
            infoFragmentInterface.getInfoFragmentData(bundle)

            navController.navigate(
                R.id.action_infoFragment_to_detailFragment,
                bundle
            )
        }
    }
}

// Create this interface to pass your data
interface InfoFragmentDataInterface {
    fun getInfoFragmentData(bundle: Any)
}

ResultsFragment

class ResultsFragment : Fragment(), InfoFragmentDataInterface {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        retainInstance = true
    }

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

    override fun onActivityCreated(savedInstanceState: Bundle?) {
        super.onActivityCreated(savedInstanceState)
        val tabLayout: TabLayout = requireView().findViewById(R.id.tabLayout_results)

        tabLayout.tabGravity = TabLayout.GRAVITY_FILL
        val tabTitles = arrayOf(
            resources.getString(R.string.result_tab1_name),
            resources.getString(R.string.result_tab2_name),
            resources.getString(R.string.result_tab3_name)
        )

        val viewPager: ViewPager = requireView().findViewById(R.id.viewpager_results)
        viewPager.offscreenPageLimit = 3
        val adapter = PagerAdapter(fragmentManager, tabTitles)
        viewPager.adapter = adapter
        tabLayout.setupWithViewPager(viewPager)
    }

    override fun getInfoFragmentData(bundle: Any) {
        // You'll get your Bundle data here.
    }
}