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

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

If you want to use ViewModels to pass data between fragments in the same activity, here's the Android documentation about it. It lets the fragments access a shared object without needing to know about each other, or communicate through the activity (with a bunch of code just to enable that communication)
You'd basically do something like this:
// create a ViewModel that holds the data you want to share
class IdentityCardViewModel : ViewModel() {
val identityInfo = MutableLiveData<IdentityCardInfo>()
fun setInfo(info: IdentityCardInfo) {
identityInfo.value = info
}
}
Then each fragment would grab a copy of the same ViewModel instance by doing:
// Get a reference to the IdentityCardViewModel created and held by the activity
private val model: IdentityCardViewModel by activityViewModels()
and then InfoFragment can set the data with model.setInfo(yourIdentityCardInfo). ResultsFragmentcan observe this data and do something whenever it sees a new value:
model.identityInfo.observe(viewLifecycleOwner, Observer<IdentityCardInfo> { info ->
// Do whatever you need with the updated info, like displaying it
})

Answer 2

#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.
}
}