I am using Recycler view with multiple views types in my project. Now when i scroll up and down the recycler view, my app crashes with a Null Pointer Exception. Here is my code of Main Adapter class.
class MainFragmentAdapter(private val myContext: MainFragment, myCallBack: MainFragment): RecyclerView.Adapter<RecyclerView.ViewHolder>(){
var gold = mutableListOf<Item>()
var silver = mutableListOf<Item>()
var advertiseBanner = mutableListOf<Window>()
var category = mutableListOf<Window>()
var mRate = mutableListOf<Rate>()
var womenSection = mutableListOf<Window>()
var menSection = mutableListOf<Window>()
var myDiscountBanner : Window ?= null
var myTrendingBanner : Window ?= null
var myFestivalBanner : Window ?= null
private val viewPool = RecyclerView.RecycledViewPool()
private val methodCallBack : MethodCallBack
init {
methodCallBack = myCallBack
}
override fun getItemViewType(position: Int): Int {
return position
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
return when(viewType){
11-> {
val binding = NewRecyclerviewBinding.inflate(LayoutInflater.from(parent.context),parent,false)
NewRecyclerViewBindingHolder(binding)
}
10-> {
val binding = AdvertiseBinding.inflate(LayoutInflater.from(parent.context),parent,false)
AdvertiseHolder(binding)
}
9-> {
val binding = DiamondBinding.inflate(LayoutInflater.from(parent.context),parent,false)
DiamondHolder(binding)
}
8 -> {
val binding = DiamondBinding.inflate(LayoutInflater.from(parent.context),parent,false)
DiamondHolder(binding)
}
7 -> {
val binding = DiamondBinding.inflate(LayoutInflater.from(parent.context),parent,false)
DiamondHolder(binding)
}
6 -> {
val binding = DiamondBinding.inflate(LayoutInflater.from(parent.context),parent,false)
DiamondHolder(binding)
}
5->{
val binding = DiamondBinding.inflate(LayoutInflater.from(parent.context),parent,false)
DiamondHolder(binding)
}
4->{
val binding = DiamondBinding.inflate(LayoutInflater.from(parent.context),parent,false)
DiamondHolder(binding)
}
3 ->{
val binding = DiamondBinding.inflate(LayoutInflater.from(parent.context),parent,false)
DiamondHolder(binding)
}
2 ->{
val binding = JewelleryPromisesBinding.inflate(LayoutInflater.from(parent.context),parent,false)
JewelleryPromisesHolder(binding)
}
1 ->{
val binding = JewelleryPromisesBinding.inflate(LayoutInflater.from(parent.context),parent,false)
JewelleryPromisesHolder(binding)
}
else ->{
val binding = JewelleryPromisesBinding.inflate(LayoutInflater.from(parent.context),parent,false)
JewelleryPromisesHolder(binding)
}
}
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
when (position) {
11 ->{
with(holder as NewRecyclerViewBindingHolder){
val categoryAdapter = CategoryAdapter()
binding.newRecyclerview.apply {
adapter = categoryAdapter
setHasFixedSize(true)
setRecycledViewPool(viewPool)
}
categoryAdapter.submitList(category)
categoryAdapter.setListener(myContext)
}
}
10 -> {
with(holder as AdvertiseHolder){
val monthly = advertiseBanner
val monthlyAdapter = MonthlyAdapter(myContext.requireContext())
monthlyAdapter.monthlyList = monthly
binding.myPager.adapter = monthlyAdapter
methodCallBack.addDotsIndicator(0,binding.linearDot,monthly.size)
binding.myPager.addOnPageChangeListener(object : ViewPager.OnPageChangeListener{
override fun onPageScrolled(
position: Int,
positionOffset: Float,
positionOffsetPixels: Int
) {
}
override fun onPageSelected(position: Int) {
methodCallBack.addDotsIndicator(
position,
binding.linearDot,
monthly.size
)
}
override fun onPageScrollStateChanged(state: Int) {
}
})
}
}
9-> {
with(holder as DiamondHolder){
if (gold.isNotEmpty()){
val goldAdapter = ProductAdapter(myContext)
goldAdapter.setListener(myContext)
if (mRate.isNotEmpty())
goldAdapter.rate = mRate[0].value!!
binding.diamondText.text = myContext.getText(R.string.gold)
binding.diamondRecycler.apply {
setHasFixedSize(true)
adapter = goldAdapter
setRecycledViewPool(viewPool)
}
goldAdapter.submitList(gold)
}
binding.viewMoreButton.setOnClickListener {
methodCallBack.click(gold)
}
}
}
8 -> {
with(holder as DiamondHolder){
binding.diamondText.visibility = View.GONE
binding.containerName.visibility = View.GONE
binding.diamondRecycler.visibility = View.GONE
binding.viewMoreButton.visibility = View.GONE
binding.showAll.visibility = View.GONE
binding.jewelleryBanner.visibility = View.VISIBLE
binding.bannerImage.loadImage(myDiscountBanner?.url)
}
}
7->{
with(holder as DiamondHolder){
if (womenSection.isNotEmpty()){
val genderAdapter = SectionAdapter()
genderAdapter.genderType = "women"
binding.viewMoreButton.visibility = View.GONE
binding.containerName.text = myContext.getText(R.string.women_section)
binding.containerName.visibility = View.VISIBLE
binding.showAll.visibility = View.VISIBLE
binding.diamondRecycler.apply {
layoutManager = GridLayoutManager(myContext.requireContext(), 3)
adapter = genderAdapter
setHasFixedSize(true)
setRecycledViewPool(viewPool)
}
genderAdapter.submitList(womenSection)
genderAdapter.setListener(myContext)
}
}
}
6 -> {
with(holder as DiamondHolder){
binding.diamondText.visibility = View.GONE
binding.containerName.visibility = View.GONE
binding.diamondRecycler.visibility = View.GONE
binding.viewMoreButton.visibility = View.GONE
binding.showAll.visibility = View.GONE
binding.jewelleryBanner.visibility = View.VISIBLE
binding.bannerImage.loadImage(myTrendingBanner?.url)
}
}
5->{
with(holder as DiamondHolder){
if (menSection.isNotEmpty()){
val genderAdapter = SectionAdapter()
genderAdapter.genderType = "men"
binding.viewMoreButton.visibility = View.GONE
binding.containerName.text = myContext.getText(R.string.men_section)
binding.containerName.visibility = View.VISIBLE
binding.showAll.visibility = View.VISIBLE
binding.diamondRecycler.apply {
layoutManager = GridLayoutManager(myContext.requireContext(), 3)
adapter = genderAdapter
setHasFixedSize(true)
setRecycledViewPool(viewPool)
}
genderAdapter.submitList(menSection)
genderAdapter.setListener(myContext)
}
}
}
4 -> {
with(holder as DiamondHolder){
binding.diamondText.visibility = View.GONE
binding.containerName.visibility = View.GONE
binding.diamondRecycler.visibility = View.GONE
binding.viewMoreButton.visibility = View.GONE
binding.showAll.visibility = View.GONE
binding.jewelleryBanner.visibility = View.VISIBLE
binding.bannerImage.loadImage(myFestivalBanner?.url)
}
}
3->{
with(holder as DiamondHolder){
if (silver.isNotEmpty()){
val goldAdapter = ProductAdapter(myContext)
goldAdapter.setListener(myContext)
if (mRate.isNotEmpty())
goldAdapter.rate = mRate[1].value!!
binding.diamondText.text = myContext.getText(R.string.silver)
binding.diamondRecycler.apply {
setHasFixedSize(true)
adapter = goldAdapter
setRecycledViewPool(viewPool)
}
goldAdapter.submitList(silver)
}
binding.viewMoreButton.setOnClickListener {
methodCallBack.click(silver)
}
}
}
2->{
with(holder as JewelleryPromisesHolder){
binding.headerTitle.visibility = View.VISIBLE
binding.table.visibility = View.VISIBLE
binding.socialFeed.visibility = View.GONE
binding.instagramIcon.visibility = View.GONE
binding.whatsappIcon.visibility = View.GONE
binding.youtubeIcon.visibility = View.GONE
binding.facebookIcon.visibility = View.GONE
}
}
1 ->{
with(holder as JewelleryPromisesHolder){
binding.headerTitle.visibility = View.GONE
binding.table.visibility = View.GONE
binding.socialFeed.visibility = View.VISIBLE
binding.instagramIcon.visibility = View.VISIBLE
binding.whatsappIcon.visibility = View.VISIBLE
binding.youtubeIcon.visibility = View.VISIBLE
binding.facebookIcon.visibility = View.VISIBLE
}
}
else -> {
with(holder as JewelleryPromisesHolder){
binding.headerTitle.visibility = View.GONE
binding.table.visibility = View.GONE
binding.socialFeed.visibility = View.GONE
binding.instagramIcon.visibility = View.GONE
binding.whatsappIcon.visibility = View.GONE
binding.youtubeIcon.visibility = View.GONE
binding.facebookIcon.visibility = View.GONE
binding.whatsappBanner.visibility = View.VISIBLE
}
}
}
}
override fun getItemCount() = 12
inner class DiamondHolder (val binding : DiamondBinding) : RecyclerView.ViewHolder(binding.root)
inner class NewRecyclerViewBindingHolder (val binding : NewRecyclerviewBinding): RecyclerView.ViewHolder(binding.root)
inner class AdvertiseHolder(val binding : AdvertiseBinding) : RecyclerView.ViewHolder(binding.root)
inner class JewelleryPromisesHolder(val binding : JewelleryPromisesBinding) : RecyclerView.ViewHolder(binding.root)
interface MethodCallBack{
fun click(productList : List<Item>)
fun click()
fun addDotsIndicator(position: Int, linearDot: LinearLayout, size: Int)
}
}
Here are my Adapter Classes codes :-
Category Adapter
class CategoryAdapter : RecyclerView.Adapter<CategoryAdapter.HorizontalHolder>() {
private var oldList = mutableListOf<Window>()
private var childListener : CategoryInterface ?= null
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): HorizontalHolder {
val binding = HorizontalCategoryBinding.inflate(LayoutInflater.from(parent.context),parent,false)
return HorizontalHolder(binding)
}
override fun onBindViewHolder(holder: HorizontalHolder, position: Int) {
with(holder){
if(oldList.isNotEmpty()) {
with(oldList[position]) {
binding.categoryImage.loadImage(this.url)
binding.categoryName.text = this.sub_type
binding.categoryImage.setOnClickListener {
childListener?.onClick(this.sub_type!!, "all")
}
}
}
}
}
fun setListener(listener : MainFragment){
childListener = listener
}
fun submitList(newList : MutableList<Window>){
val diffUtil = WindowDiffUtil(oldList ,newList)
val diffResult = DiffUtil.calculateDiff(diffUtil)
oldList = newList
diffResult.dispatchUpdatesTo(this)
}
override fun getItemCount() = oldList.size
inner class HorizontalHolder(val binding : HorizontalCategoryBinding) : RecyclerView.ViewHolder(binding.root)
}
Product Adapter
class ProductAdapter(private val context : MainFragment) : RecyclerView.Adapter<ProductAdapter.ProductHolder>(){
var itemList = mutableListOf<Item>()
var rate = 0
private var childListener : ChildInterface ?= null
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ProductHolder {
val binding = SilverCardsBinding.inflate(LayoutInflater.from(parent.context),parent,false)
return ProductHolder(binding)
}
override fun onBindViewHolder(holder: ProductHolder, position: Int) {
with(holder){
if (itemList.isNotEmpty()) {
with(itemList[position]) {
if (rate != 0) {
binding.productImage.loadImage(this.images?.get(0))
binding.itemName.text = this.name
var weight = this.net_weight
if (weight != null) {
weight *= (rate)
}
val newWeight = weight?.toInt()?.plus(this.labour!!)
binding.price.text =
context.resources.getString(R.string.Rs, newWeight?.toString())
holder.itemView.setOnClickListener {
childListener?.onClick(this, "SelectedProduct")
}
}
}
}
}
}
fun submitList(newList : MutableList<Item>){
val diffUtil = ItemDiffUtil(itemList ,newList)
val diffResult = DiffUtil.calculateDiff(diffUtil)
itemList = newList
diffResult.dispatchUpdatesTo(this)
}
fun setListener(listener : MainFragment){
childListener = listener
}
override fun getItemCount() : Int {
return itemList.size
}
inner class ProductHolder(val binding : SilverCardsBinding): RecyclerView.ViewHolder(binding.root)
}
SectionAdapter
class SectionAdapter : RecyclerView.Adapter<SectionAdapter.SectionHolder>(){
private var oldList = mutableListOf<Window>()
var genderType : String ?= null
private var childListener : CategoryInterface?= null
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): SectionHolder {
val binding = SectionBinding.inflate(LayoutInflater.from(parent.context), parent, false)
return SectionHolder(binding)
}
override fun onBindViewHolder(holder: SectionHolder, position: Int) {
if (oldList.isNotEmpty()) {
with(holder){
with(oldList[position]) {
binding.sectionImage.loadImage(this.url)
binding.sectionName.text = this.sub_type
holder.itemView.setOnClickListener {
childListener?.onClick(this.sub_type!!, genderType!!)
}
}
}
}
}
override fun getItemCount(): Int {
return oldList.size
}
fun setListener(listener : MainFragment){
childListener = listener
}
fun submitList(newList : MutableList<Window>){
val diffUtil = WindowDiffUtil(oldList ,newList)
val diffResult = DiffUtil.calculateDiff(diffUtil)
oldList = newList
diffResult.dispatchUpdatesTo(this)
}
inner class SectionHolder (val binding : SectionBinding) : RecyclerView.ViewHolder(binding.root){
}
}
Now when I scroll fast, I get Null Pointer Exception. These are the exceptions.
java.lang.ClassCastException: com.example.groceryapp.mainscreen.CategoryAdapter$HorizontalHolder cannot be cast to com.example.groceryapp.mainscreen.SectionAdapter$SectionHolder
at com.example.groceryapp.mainscreen.SectionAdapter.onBindViewHolder(SectionAdapter.kt:14)
at androidx.recyclerview.widget.RecyclerView$Adapter.onBindViewHolder(RecyclerView.java:7254)
at androidx.recyclerview.widget.RecyclerView$Adapter.bindViewHolder(RecyclerView.java:7337)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryBindViewHolderByDeadline(RecyclerView.java:6194)
at androidx.recyclerview.widget.RecyclerView$Recycler.tryGetViewHolderForPositionByDeadline(RecyclerView.java:6460)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6300)
at androidx.recyclerview.widget.RecyclerView$Recycler.getViewForPosition(RecyclerView.java:6296)
at androidx.recyclerview.widget.LinearLayoutManager$LayoutState.next(LinearLayoutManager.java:2330)
at androidx.recyclerview.widget.GridLayoutManager.layoutChunk(GridLayoutManager.java:572)
at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1591)
at androidx.recyclerview.widget.LinearLayoutManager.onLayoutChildren(LinearLayoutManager.java:668)
at androidx.recyclerview.widget.GridLayoutManager.onLayoutChildren(GridLayoutManager.java:170)
at androidx.recyclerview.widget.RecyclerView.dispatchLayoutStep2(RecyclerView.java:4309)
at androidx.recyclerview.widget.RecyclerView.onMeasure(RecyclerView.java:3686)
at android.view.View.measure(View.java:24530)
at androidx.constraintlayout.widget.ConstraintLayout$Measurer.measure(ConstraintLayout.java:811)
at androidx.constraintlayout.core.widgets.ConstraintWidgetContainer.measure(ConstraintWidgetContainer.java:632)
at androidx.constraintlayout.core.widgets.analyzer.Direct.horizontalSolvingPass(Direct.java:323)
at androidx.constraintlayout.core.widgets.analyzer.Direct.solveHorizontalMatchConstraint(Direct.java:709)
at androidx.constraintlayout.core.widgets.analyzer.Direct.horizontalSolvingPass(Direct.java:374)
at androidx.constraintlayout.core.widgets.analyzer.Direct.solvingPass(Direct.java:144)
at androidx.constraintlayout.core.widgets.ConstraintWidgetContainer.layout(ConstraintWidgetContainer.java:693)
at androidx.constraintlayout.core.widgets.analyzer.BasicMeasure.solveLinearSystem(BasicMeasure.java:160)
at androidx.constraintlayout.core.widgets.analyzer.BasicMeasure.solverMeasure(BasicMeasure.java:291)
at androidx.constraintlayout.core.widgets.ConstraintWidgetContainer.measure(ConstraintWidgetContainer.java:120)
at androidx.constraintlayout.widget.ConstraintLayout.resolveSystem(ConstraintLayout.java:1594)
at androidx.constraintlayout.widget.ConstraintLayout.onMeasure(ConstraintLayout.java:1708)
at android.view.View.measure(View.java:24530)
at androidx.recyclerview.widget.RecyclerView$LayoutManager.measureChildWithMargins(RecyclerView.java:9681)
at androidx.recyclerview.widget.LinearLayoutManager.layoutChunk(LinearLayoutManager.java:1657)
at androidx.recyclerview.widget.LinearLayoutManager.fill(LinearLayoutManager.java:1591)
at androidx.recyclerview.widget.LinearLayoutManager.scrollBy(LinearLayoutManager.java:1395)
at androidx.recyclerview.widget.LinearLayoutManager.scrollVerticallyBy(LinearLayoutManager.java:1136)
at androidx.recyclerview.widget.RecyclerView.scrollStep(RecyclerView.java:1972)
at androidx.recyclerview.widget.RecyclerView.scrollByInternal(RecyclerView.java:2071)
at androidx.recyclerview.widget.RecyclerView.onTouchEvent(RecyclerView.java:3531)
at android.view.View.dispatchTouchEvent(View.java:13415)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3054)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2741)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3060)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2755)
2022-10-25 22:09:51.133 26193-26193 AndroidRuntime com.example.groceryapp E at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3060)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2755)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3060)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2755)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3060)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2755)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3060)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2755)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3060)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2755)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3060)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2755)
at android.view.ViewGroup.dispatchTransformedTouchEvent(ViewGroup.java:3060)
at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:2755)
at com.android.internal.policy.DecorView.superDispatchTouchEvent(DecorView.java:465)
at com.android.internal.policy.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1849)
.....
