I have a generic list that need to be show on most of the activities/fragments throughout my app. For this I have created a layout and added the recycler in it as in below code. This layout is then included in the activities/fragment where required. I am using MVVM and android bindings.My problem here is that the recyclerview`s onCreateViewHolder or even getItemCount is never called. My updateList function is called successfully from viewmodel with 2 items in the list but notifydatasetchanged has no effect as all. What i am doing wrong? Here is my code. Adapter Class
class FaqsAdapter : RecyclerView.Adapter<FaqsAdapter.MyViewHolder>() {
lateinit var binding: FaqItemBinding
lateinit var listFaqs: List<ModelFaqs>
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val inflater = LayoutInflater.from(parent.context)
binding = DataBindingUtil.inflate(inflater, R.layout.faq_item, parent, false)
return MyViewHolder(binding)
}
override fun getItemCount(): Int {
return if (::listFaqs.isInitialized) listFaqs.size else 0
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
holder.bind(listFaqs[position])
}
fun updateList(faqs: List<ModelFaqs>) {
this.listFaqs = faqs //this line executes
notifyDataSetChanged() // line also executes but does nothing.
}
class MyViewHolder(binding: FaqItemBinding) : RecyclerView.ViewHolder(binding.root) {
private val mBinding = binding
fun bind(modelFaqs: ModelFaqs) {
val viewModel = FaqItemViewModel()
viewModel.bind(modelFaqs)
mBinding.mViewModel = viewModel
}
}
}
Fragment
class FragLoan : Fragment() {
//other code
override fun onActivityCreated(savedInstanceState: Bundle?) {
super.onActivityCreated(savedInstanceState)
binding.viewFaqs.rcFaqs.layoutManager = LinearLayoutManager(context)
viewModel = ViewModelProviders.of(this).get(FragLoanViewModel::class.java)
}
}
The viewModel class
class FragLoanViewModel : BaseViewModel() {
//other code
private fun onLoanSuccess(response: AdvanceLoanDetails?) {
Log.d(TAG, "LoanViewModel--On Success")
val modelFaqs: MutableList<ModelFaqs> = mutableListOf()
if (response?.result == true) {
if (response.resultContent?.faqs != null) {
for (faqs in response.resultContent.faqs) {
val model = ModelFaqs(faqs?.question, faqs?.answer)
modelFaqs.add(model)
}
updateFaq(modelFaqs)
}
}
}
//other code.
}
Base ViewModel This is my baseviewModel
abstract class BaseViewModel : ViewModel() {
val faqsAdapter = FaqsAdapter()
private val injector: ViewModelInjector = DaggerViewModelInjector
.builder()
.networkModule(NetworkModule)
.build()
init {
inject()
}
private fun inject() {
when (this) {
//code here
}
}
fun updateFaq(listFaqs: List<ModelFaqs>) {
faqsAdapter.updateList(listFaqs)
}
}
The fragment Layout
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
xmlns:tools="http://schemas.android.com/tools">
<data>
<variable
name="viewModel"
type="com.mypackage.viewmodel.FragLoanViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="@color/colorViewBackgroundGrey"
tools:context="com.mypackage.myfragments.FragLoan">
<ImageView
android:id="@+id/ivLoanBanner"
android:layout_width="0dp"
android:layout_height="@dimen/_60sdp"
android:layout_marginTop="16dp"
android:contentDescription="@null"
android:scaleType="fitXY"
app:imageurl="@{viewModel.banner}"
app:layout_constraintLeft_toLeftOf="@id/guideLeft"
app:layout_constraintRight_toRightOf="@id/guideRight"
app:layout_constraintTop_toTopOf="parent" />
<androidx.cardview.widget.CardView
android:id="@+id/cvLoanDetails"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:background="@color/colorWhite"
app:cardCornerRadius="@dimen/card_content_radius"
app:layout_constraintEnd_toEndOf="@id/guideRight"
app:layout_constraintStart_toStartOf="@id/guideLeft"
app:layout_constraintTop_toBottomOf="@id/ivLoanBanner">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_margin="@dimen/_16sdp">
<TextView
android:id="@+id/tvAdvanceLoadTitle"
mutableText="@{viewModel.title}"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="@dimen/_6sdp"
android:textColor="@color/colorBlack"
android:textStyle="bold"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/tvAdvanceLoanValidity"
mutableText="@{viewModel.validity}"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="3dp"
android:textColor="@color/lightGrey"
app:layout_constraintStart_toStartOf="@+id/tvAdvanceLoadTitle"
app:layout_constraintTop_toBottomOf="@+id/tvAdvanceLoadTitle" />
<TextView
android:id="@+id/tvAdvanceLoanPrice"
mutableText="@{viewModel.amount}"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="@color/colorPrimary"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="@+id/tvAdvanceLoadTitle" />
<TextView
android:id="@+id/tvAdvanceLoanTax"
mutableText="@{viewModel.inclusiveTax}"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="3dp"
android:textColor="@color/lightGrey"
app:layout_constraintEnd_toEndOf="@+id/tvAdvanceLoanPrice"
app:layout_constraintTop_toBottomOf="@+id/tvAdvanceLoanPrice" />
<TextView
android:id="@+id/tvAdvanceLoanDetail"
mutableText="@{viewModel.description}"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="@dimen/_8sdp"
android:background="@drawable/edit_text_history"
android:gravity="center"
android:minHeight="@dimen/_50sdp"
android:padding="@dimen/_6sdp"
android:textColor="@color/lightGrey"
android:textSize="12sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/tvAdvanceLoanValidity" />
<androidx.constraintlayout.widget.Barrier
android:id="@+id/barrier"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
app:barrierDirection="left"
app:constraint_referenced_ids="tvAdvanceLoanTax,tvAdvanceLoanPrice"
tools:layout_editor_absoluteX="369dp" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
<androidx.constraintlayout.widget.Guideline
android:id="@+id/guideLeft"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_begin="16dp" />
<androidx.constraintlayout.widget.Guideline
android:id="@+id/guideRight"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:orientation="vertical"
app:layout_constraintGuide_end="16dp" />
<!-- <androidx.recyclerview.widget.RecyclerView-->
<!-- android:id="@+id/rcFaqs"-->
<!-- app:layout_constraintEnd_toEndOf="@id/guideRight"-->
<!-- app:layout_constraintStart_toStartOf="@id/guideLeft"-->
<!-- app:layout_constraintTop_toBottomOf="@+id/cvLoanDetails"-->
<!-- android:layout_width="0dp"-->
<!-- android:layout_height="wrap_content"-->
<!-- app:adapter="@{viewModel.faqsAdapter}" />-->
<include
android:id="@+id/viewFaqs"
layout="@layout/view_faq"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
app:layout_constraintEnd_toEndOf="@id/guideRight"
app:layout_constraintStart_toStartOf="@id/guideLeft"
app:layout_constraintTop_toBottomOf="@+id/cvLoanDetails" />
<include
android:id="@+id/viewTerms"
layout="@layout/view_terms_conditions"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
app:layout_constraintEnd_toEndOf="@id/guideRight"
app:layout_constraintStart_toStartOf="@id/guideLeft"
app:layout_constraintTop_toBottomOf="@+id/viewFaqs" />
<com.google.android.material.button.MaterialButton
android:id="@+id/btnGetLoan"
android:layout_width="0dp"
android:layout_height="@dimen/button_height"
android:layout_marginBottom="8dp"
android:text="@string/get_loan"
android:textAllCaps="false"
app:cornerRadius="@dimen/button_corner_radius"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="@id/guideRight"
app:layout_constraintStart_toStartOf="@id/guideLeft" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
My FaqItemViewModel
class FaqItemViewModel : BaseViewModel() {
private val sequenceNumber = MutableLiveData<String>()
private val question = MutableLiveData<String>()
private val answer = MutableLiveData<String>()
private var sqNo = 0
fun bind(faqs: ModelFaqs) {
sqNo += 1
sequenceNumber.value = sqNo.toString()
question.value = faqs.question
answer.value = faqs.answer
}
fun getSequenceNumber(): MutableLiveData<String> {
return sequenceNumber
}
fun getQuestion(): MutableLiveData<String> {
return question
}
fun getAnswer(): MutableLiveData<String> {
return answer
}
}
and Item XML
<?xml version="1.0" encoding="utf-8"?>
<layout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto">
<data>
<variable
name="mViewModel"
type="com.mypackage.viewmodel.FaqItemViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">
<TextView
android:id="@+id/tvSerialNumber"
mutableText="@{mViewModel.sequenceNumber}"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="@color/colorAccent"
android:textStyle="bold"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="@+id/tvQuestion"
mutableText="@{mViewModel.question}"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:paddingLeft="6dp"
android:paddingRight="6dp"
android:textColor="@color/colorAccent"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="@+id/tvSerialNumber"
app:layout_constraintTop_toTopOf="@+id/tvSerialNumber" />
<TextView
android:id="@+id/tvAnswer"
mutableText="@{mViewModel.answer}"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginTop="8dp"
android:paddingLeft="6dp"
android:paddingRight="6dp"
android:textColor="@color/lightGrey"
android:textSize="12sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="@+id/tvQuestion"
app:layout_constraintTop_toBottomOf="@+id/tvQuestion" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
The issue is now resolved. I searched for examples on the internet and found google sample app sunflowerAlpha. After looking around this code I made few changes to mine. like first i remove these lines from BaseView model
val faqsAdapter = FaqsAdapter()
fun updateFaq(listFaqs: List<ModelFaqs>) {
faqsAdapter.updateList(listFaqs)
}
and then I remove adapter binding "app:adapter="@{theviewmodel.myAdapter}" from xml file and bind the adapter from my Fragment like this.
binding.viewFaqs.rcFaqs.layoutManager = LinearLayoutManager(context)
binding.viewFaqs.rcFaqs.isNestedScrollingEnabled = false
binding.viewFaqs.rcFaqs.adapter = faqsAdapter
val faqs = createFaqs(loanDetails)
faqsAdapter.updateList(faqs)
Now the recyclerview is successfully populated.