Develop Reference

Having the same error but unable to solve it

I'm pretty new at android development, and I'm trying to fetch data from Realtime Database into recycler view in a fragment. I've seen pretty much every tutorial how to do it but it simply wont work. Below I'll put the source code.
main fragment (where i need to fetch the data)
package hr.ferit.tomislav.lucic5.tl5_projekt
import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProvider
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.google.android.material.floatingactionbutton.FloatingActionButton
import com.google.firebase.database.*
private lateinit var transactions : ArrayList<Transaction>
private lateinit var recyclerView : RecyclerView
private lateinit var adapter: TransactionAdapter
private lateinit var loadingData : TextView
private lateinit var dbRef : DatabaseReference
class MainFragment : Fragment() {
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
val view = inflater.inflate(R.layout.fragment_main, container, false)
return view
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
val newTransaction = view.findViewById<FloatingActionButton>(R.id.addBtn)
recyclerView = view.findViewById(R.id.recyclerview)
recyclerView.layoutManager = LinearLayoutManager(context)
recyclerView.setHasFixedSize(true)
loadingData = view.findViewById(R.id.tvLoadingData)
transactions = arrayListOf<Transaction>()
getTransactionData()
newTransaction?.setOnClickListener {
val homeFragment = AddTransactionFragment()
val transaction = fragmentManager?.beginTransaction()
transaction?.replace(R.id.mainFrame,homeFragment)
transaction?.addToBackStack(null)
transaction?.commit()
}
}
private fun updateDashboard(){
var balance = view?.findViewById<TextView>(R.id.balance)
var expense = view?.findViewById<TextView>(R.id.expense)
var budget = view?.findViewById<TextView>(R.id.budget)
val totalAmount = transactions.map { it.amount.toInt() }.sum()
val budgetAmount = transactions.filter { it.amount.toInt() >0 }.map{it.amount.toInt()}.sum()
val expenseAmount = totalAmount - budgetAmount
balance?.text = "$ %.2f".format(totalAmount)
budget?.text = "$ %.2f".format(budgetAmount)
expense?.text = "$ %.2f".format(expenseAmount)
}
private fun getTransactionData(){
recyclerView.visibility= View.GONE
loadingData.visibility = View.VISIBLE
dbRef = FirebaseDatabase.getInstance().getReference("transactions")
dbRef.addValueEventListener(object: ValueEventListener {
override fun onDataChange(snapshot: DataSnapshot) {
transactions.clear()
if (snapshot.exists()) {
for (tranSnap in snapshot.children) {
val tranData =
tranSnap.getValue(Transaction::class.java)
transactions.add(tranData!!)
}
val mAdapter = TransactionAdapter(transactions)
recyclerView.adapter = mAdapter
recyclerView.visibility = View.VISIBLE
loadingData.visibility = View.GONE
}
}
override fun onCancelled(error: DatabaseError) {
TODO("Not yet implemented")
}
})
}
}
adapter
package hr.ferit.tomislav.lucic5.tl5_projekt
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
class TransactionAdapter(private val trList:ArrayList<Transaction>) :
RecyclerView.Adapter<TransactionAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(R.layout.transaction_layout,parent,false)
return ViewHolder(itemView)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
val curTransaction = trList[position]
holder.amount.text = curTransaction.amount
holder.label.text = curTransaction.label
}
override fun getItemCount(): Int {
return trList.size
}
fun addItem(transaction: Transaction){
trList.add(0, transaction)
notifyItemInserted(0)
}
class ViewHolder(itemView: View): RecyclerView.ViewHolder(itemView){
val label : TextView = itemView.findViewById(R.id.label)
val amount : TextView = itemView.findViewById(R.id.amount)
}
}
data class for Transaction
package hr.ferit.tomislav.lucic5.tl5_projekt
data class Transaction (
var label: String,
var amount: String,
var description: String
)
I don't know what can I do else.. it's always the same error Class hr.ferit.tomislav.lucic5.tl5_projekt.Transaction does not define a no-argument constructor. If you are using ProGuard, make sure these constructors are not stripped. That happens after i try to add a new transaction:
package hr.ferit.tomislav.lucic5.tl5_projekt
import android.annotation.SuppressLint
import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.ImageButton
import androidx.core.widget.addTextChangedListener
import com.google.android.material.textfield.TextInputEditText
import com.google.android.material.textfield.TextInputLayout
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.database.FirebaseDatabase
import com.google.firebase.database.ktx.database
import com.google.firebase.ktx.Firebase
class AddTransactionFragment : Fragment() {
private lateinit var database : FirebaseDatabase
#SuppressLint("MissingInflatedId")
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(R.layout.fragment_add_transaction2, container, false)
val addBtn = view.findViewById<Button>(R.id.addTransactionBtn)
val titleInput = view.findViewById<TextInputEditText>(R.id.titleInput)
val amountInput = view.findViewById<TextInputEditText>(R.id.amountInput)
val descriptionInput = view.findViewById<TextInputEditText>(R.id.descriptionInput)
val titleLayout = view.findViewById<TextInputLayout>(R.id.titleLayout)
val amountLayout = view.findViewById<TextInputLayout>(R.id.amountLayout)
val closeBtn = view.findViewById<ImageButton>(R.id.closeBtn)
var recyclerAdapter : TransactionAdapter
var database = Firebase.database.reference
val userId = FirebaseAuth.getInstance().currentUser!!.uid
titleInput.addTextChangedListener {
if(it!!.count() > 0)
titleLayout.error = null
}
amountInput.addTextChangedListener {
if(it!!.count() > 0)
amountLayout.error = null
}
addBtn.setOnClickListener{
val title = titleInput.text.toString()
val description = descriptionInput.text.toString()
val amount = amountInput.text.toString()
var transactionToAdd = Transaction(
label = titleInput.text.toString(),
description = descriptionInput.text.toString(),
amount = amountInput.text.toString()
)
val list = ArrayList<Transaction>()
recyclerAdapter = TransactionAdapter(list)
if(title.isEmpty()) {
titleLayout.error = "Please enter a valid title"
}
if(amount.isEmpty()) {
amountLayout.error = "Please enter a valid amount"
}
else{
database.child("transactions").push().setValue(transactionToAdd)
.addOnSuccessListener {
recyclerAdapter.addItem(transactionToAdd)
var homeFragment = MainFragment()
val transaction = fragmentManager?.beginTransaction()
transaction?.replace(R.id.mainFrame,homeFragment)
transaction?.commit()
}
}
}
closeBtn.setOnClickListener{
var homeFragment = MainFragment()
val transaction = fragmentManager?.beginTransaction()
transaction?.replace(R.id.mainFrame,homeFragment)
transaction?.commit()
}
return view
}
}
I tried everything, basically every tutorial I found on youtube but nothing helped. I don't know what's the problem, I get that it is something to do with the data class and the constructor but im unable to solve it.

Android Studio Kotlin, notifyItemChanged not calling OnBindViewHolder

I am trying to make a game of life grid based game in Android Studio using kotlin. Essentially, every second the grid will update based off a set of rules. However, I can not for the life of me get the grid to update.
For some reason, notifyItemChanged() is not calling onBindViewHolder to properly update the grid visually. I was able to find a work around for some cases, that being calling onBindViewHolder specifically and passing through the current cellViewHolder and it's position, but this won't get me the result I am looking for. Specifically, in the function I declared testUpdate(), I need to be able to change an array of data that the grid is based on, and then from that function notify the grid that changes were made and it should update. However, notifyItemChanged() as well as notifyDatasetChanged() both do not call onBindViewHolder(). I am at a loss, any help would be much appreciated!
I am very new to Kotlin, so I apologize if this code is horrible.
Here is my code:
package com.example.project2
import android.graphics.Color
import android.os.Bundle
import android.text.Layout
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.ImageButton
import android.widget.TextView
import androidx.fragment.app.Fragment
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
import android.os.Handler;
class BoardFragment : Fragment() {
private lateinit var recyclerView: RecyclerView
var gridArray = IntArray(400)
val handler = Handler()
var isRunning: Boolean = false
val colorRed = Color.RED
val colorBlue = Color.BLUE
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(R.layout.board_fragment, container, false)
val startButton = view.findViewById(R.id.start_button) as Button
val recyclerView = view.findViewById(R.id.recycler_view) as RecyclerView
recyclerView.layoutManager = GridLayoutManager(activity, 20)
recyclerView.adapter = GridAdapter()
startButton.setOnClickListener {
isRunning = !isRunning
if (isRunning) {
testUpdate()
}
}
return view
}
fun testUpdate() {
handler.postDelayed({
if (gridArray[3] == 0) {
gridArray[3] = 1
} else {
gridArray[3] = 0
}
if (isRunning) {
testUpdate()
}
GridAdapter().notifyItemChanged(3)
}, 1000)
}
override fun onStart() {
super.onStart()
}
private inner class CellViewHolder(cellView: View): RecyclerView.ViewHolder(cellView) {
val button: ImageButton
init {
button = cellView.findViewById(R.id.cell_button)
button.setColorFilter(null)
button.setOnClickListener {
if (gridArray[position] == 0) {
gridArray[position] = 1
} else {
gridArray[position] = 0
}
GridAdapter().notifyItemChanged(position)
GridAdapter().onBindViewHolder(this, position)
}
}
fun display(position: Int) {
}
}
private inner class GridAdapter: RecyclerView.Adapter<CellViewHolder>() {
final val NUM_CELLS: Int = 400
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CellViewHolder {
val inflater: LayoutInflater = LayoutInflater.from(parent.context)
val cellView: View = inflater.inflate(R.layout.board_cell, parent, false)
return CellViewHolder(cellView)
}
override fun onBindViewHolder(holder: CellViewHolder, position: Int) {
holder.display(position)
if (gridArray[position] == 0) {
holder.button.setColorFilter(null)
} else {
holder.button.setColorFilter(Color.RED)
}
}
override fun getItemCount(): Int {
return NUM_CELLS
}
}
}

I don't know what you're trying to achieve but a few tip
notifyItemChange() should be called from the Adapter class.
You're creating a new instances of GridAdapter GridAdapter().notifyItemChanged(position)
change
GridAdapter().notifyItemChanged(position)
to
recyclerView.adapter.notifyItemChanged(position)
modify your class like this
package com.example.project2
import android.graphics.Color
import android.os.Bundle
import android.text.Layout
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.ImageButton
import android.widget.TextView
import androidx.fragment.app.Fragment
import androidx.recyclerview.widget.GridLayoutManager
import androidx.recyclerview.widget.RecyclerView
import android.os.Handler;
class BoardFragment : Fragment() {
private lateinit var recyclerView: RecyclerView
var gridArray = IntArray(400)
val handler = Handler()
var isRunning: Boolean = false
val colorRed = Color.RED
val colorBlue = Color.BLUE
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
}
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val view = inflater.inflate(R.layout.board_fragment, container, false)
val startButton = view.findViewById(R.id.start_button) as Button
val recyclerView = view.findViewById(R.id.recycler_view) as RecyclerView
recyclerView.layoutManager = GridLayoutManager(activity, 20)
recyclerView.adapter = GridAdapter()
startButton.setOnClickListener {
isRunning = !isRunning
if (isRunning) {
testUpdate()
}
}
return view
}
fun testUpdate() {
handler.postDelayed({
if (gridArray[3] == 0) {
gridArray[3] = 1
} else {
gridArray[3] = 0
}
if (isRunning) {
testUpdate()
}
recyclerView.adapter.notifyItemChanged(3)
}, 1000)
}
override fun onStart() {
super.onStart()
}
private inner class CellViewHolder(cellView: View): RecyclerView.ViewHolder(cellView) {
val button: ImageButton
init {
button = cellView.findViewById(R.id.cell_button)
button.setColorFilter(null)
button.setOnClickListener {
if (gridArray[position] == 0) {
gridArray[position] = 1
} else {
gridArray[position] = 0
}
}
}
fun display(position: Int) {
}
}
private inner class GridAdapter: RecyclerView.Adapter<CellViewHolder>() {
final val NUM_CELLS: Int = 400
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): CellViewHolder {
val inflater: LayoutInflater = LayoutInflater.from(parent.context)
val cellView: View = inflater.inflate(R.layout.board_cell, parent, false)
return CellViewHolder(cellView)
}
override fun onBindViewHolder(holder: CellViewHolder, position: Int) {
if (gridArray[position] == 0) {
holder.button.setColorFilter(null)
} else {
holder.button.setColorFilter(Color.RED)
}
holder.display(position)
recyclerView.adapter.notifyItemChanged(3)
}
override fun getItemCount(): Int {
return NUM_CELLS
}
}
}

Error when setting button inside recycler view?

I get error when I press button inside recycler view. My application is not crashing. I am trying to set a button in the recycler view and callingsetOnClickListener inside onBindViewHolder. Inside the holder.Button.setOnClickListener{}I change the button text to notified. But when I press a button the values of other button text in another list also changes. This is a listview of firestore documents. I have many documents that are uploaded into the recycler view. If I am getting the error how should I implement the button onclicklistener without this error.[![https://i.stack.imgur.com/S0Oxm.jpg][1]][1] [![enter image description here][2]][2]
/**This my activity for recycler view*/
package com.example.bloodbankcompany.recyclerview
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.Adapter
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.example.bloodbankcompany.MyAdapter
import com.example.bloodbankcompany.R
import com.example.bloodbankcompany.User1
import com.example.bloodbankcompany.User2
import com.google.firebase.firestore.*
import java.lang.NullPointerException
class MainActivity2 : AppCompatActivity() {
private lateinit var recyclerView: RecyclerView
private lateinit var userArrayList: ArrayList<User2>
private lateinit var myAdapter: MyAdapter2
private val mFireStore = FirebaseFirestore.getInstance()
var db = FirebaseFirestore.getInstance()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main2)
recyclerView= findViewById(R.id.recyclerview)
recyclerView.layoutManager = LinearLayoutManager(this)
recyclerView.setHasFixedSize(true)
userArrayList= arrayListOf()
myAdapter =MyAdapter2(userArrayList)
recyclerView.adapter = myAdapter
EventChangeListener()
}
private fun EventChangeListener() {
try {
mFireStore.collection("applicationForm").addSnapshotListener(object :
EventListener<QuerySnapshot> {
override fun onEvent(value: QuerySnapshot?, error: FirebaseFirestoreException?) {
if (error != null) {
Log.e("firestore error", error.message.toString())
}
try {
for (dc: DocumentChange in value?.documentChanges!!) {
if (dc.type == DocumentChange.Type.ADDED) {
userArrayList.add(dc.document.toObject(User2::class.java))
}
// Toast.makeText(applicationContext,userArrayList.toString(), Toast.LENGTH_SHORT).show()
}
} catch (e:NullPointerException){
}
myAdapter.notifyDataSetChanged()
}
})
} catch (e:NullPointerException){
}
}
}
/**
* This is my myAdapter activity for adapater*/
package com.example.bloodbankcompany.recyclerview
import android.content.Intent
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Button
import android.widget.TextView
import android.widget.Toast
import androidx.recyclerview.widget.RecyclerView
import com.example.bloodbankcompany.R
import com.example.bloodbankcompany.RegisterActivity
import com.example.bloodbankcompany.User2
import com.google.firebase.firestore.FirebaseFirestore
import kotlinx.android.synthetic.main.list_item2.view.*
class MyAdapter2(private val userList: ArrayList<User2>): RecyclerView.Adapter<MyAdapter2.MyViewHolder>(){
var id: String = ""
private val mFireStore = FirebaseFirestore.getInstance()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyAdapter2.MyViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(R.layout.list_item2,parent,false)
return MyViewHolder(itemView)
}
override fun onBindViewHolder(holder: MyAdapter2.MyViewHolder, position: Int) {
val user:User2 = userList[position]
holder.name.text= user.name
holder.phone.text= user.phone
holder.address.text =user.address
holder.bloodGroup.text= user.bloodgroup
holder.id.text = user.id
//Setting onclicklistener to my adapter and starting intent
holder.button.setOnClickListener {
// holder.io = "kkj"
// holder.id.text = " "
holder.button.setText("notified")
// val context=holder.button.context
// val intent = Intent( context, RegisterActivity::class.java)
// context.startActivity(intent)
}
}
override fun getItemCount(): Int {
return userList.size
}
public class MyViewHolder(itemView : View): RecyclerView.ViewHolder(itemView){
val name : TextView = itemView.findViewById(R.id.tvfirstname1)
val phone :TextView= itemView.findViewById(R.id.tvphone11)
val address : TextView= itemView.findViewById(R.id.tvaddress1)
val bloodGroup: TextView =itemView.findViewById(R.id.tvbloodg1)
val id: TextView = itemView.findViewById(R.id.tvid)
var io: String? = ""
var button: Button = itemView.findViewById(R.id.btn_notify)
class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView){
init {
itemView.btn_notify.setOnClickListener {
}
}
}
}
} ```
[1]: https://i.stack.imgur.com/S0Oxm.jpg
[2]: https://i.stack.imgur.com/BqDMf.jpg

create interface for clickListener in your adapter and set it in constructor
interface OnItemClickListener {
fun onItemClick(position: Int)
}
and in ViewHolder set bind your button
fun bind(position: Int, listener: OnItemClickListener) {
button.setOnClickListener { v -> listener.onItemClick(position) }
}
and then set this code in onBindViewHolder
holder.bind( position , onItemClickListener)
finally when click on button you can action in Activity or Fragment
example :
adapter = Adapter(getContext(), models) { position -> }

Simple Code, Without using Interface
Actually what I found is you were doing it the correct way, but you were using two ViewHolder classes there which is the cause of issue. Try to use the below code once and try again. Hope it works.
class mAdapter(val context: Context, private val dataList: ArrayList<String>):
RecyclerView.Adapter<mAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): mAdapter.ViewHolder {
val v = LayoutInflater.from(parent.context).inflate(R.layout.item_card_view, parent, false)
return mAdapter.ViewHolder(v)
}
override fun onBindViewHolder(holder: mAdapter.ViewHolder, position: Int) {
holder.txtView.setText(dataList.get(position))
//Your Button setOnClickLister
holder.btnName.setOnClickListener {
// action here
}
}
override fun getItemCount(): Int {
return dataList.size
}
class ViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
val txtView = itemView.findViewById(R.id.textView) as TextView
val btnName = itemView.findViewById(R.id.btnName) as Button
}
}

RecyclerView , kotlin, click response delay

Peace
i have made simple recyclerview, with interface clickListener
consisting of 4 items showing toast on click.
It works fine if i single click per second,
but if i Rapidly click on different items ( 2 or 3 times in 1 seconds )
it still shows the toast each second,
not rapidly changing the toast
data class code:
package com.elsersy.rv5
data class Items (var textt:String) {
}
adapter code
package com.elsersy.rv5
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.RecyclerView
class MyAdapter(private var stringList:ArrayList<Items>,private val listener:MyOnClickListener):
RecyclerView.Adapter<MyAdapter.MyViewHolder>() {
inner class MyViewHolder(itemView:View):RecyclerView.ViewHolder(itemView) {
var text:TextView = itemView.findViewById(R.id.textView)
init {
itemView.setOnClickListener {
val position = absoluteAdapterPosition
if (position != RecyclerView.NO_POSITION)
{
listener.onItemClick(position)
}
}
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(R.layout.row_item,parent,false)
return MyViewHolder(itemView)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val currentItem = stringList[position]
holder.text.text = currentItem.textt
}
override fun getItemCount(): Int {
return stringList.size
}
interface MyOnClickListener{
fun onItemClick(position: Int)
}
fun setData(newItemList:ArrayList<Items>){
val diffUtil = MyDiffUtil(stringList,newItemList)
val diffResults = DiffUtil.calculateDiff(diffUtil)
stringList = newItemList
diffResults.dispatchUpdatesTo(this)
}
}
ActivityMainCode
package com.elsersy.rv5
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import com.elsersy.rv5.databinding.ActivityMainBinding
class MainActivity : AppCompatActivity(),MyAdapter.MyOnClickListener {
private lateinit var binding: ActivityMainBinding
private lateinit var stringList:ArrayList<Items>
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
val view = binding.root
setContentView(view)
binding.recyclerView.layoutManager = LinearLayoutManager(this)
stringList = arrayListOf<Items>()
getStrings()
binding.recyclerView.adapter=MyAdapter(stringList,this)
}
private fun getStrings() {
for (a in 0..4){
var string_Array = resources.getStringArray(R.array.string_array)
stringList.add(Items(string_Array[a]))
}
}
override fun onItemClick(position: Int) {
Toast.makeText(this,"$position is clicked", Toast.LENGTH_SHORT).show()
}
}

If you want to cancel the previous toast before showing a new one, assign it as a member variable and cancel it before showing the new one:
private var toast : Toast? = null
..
override fun onItemClick(position: Int) {
toast?.cancel()
toast = Toast.makeText(this,"$position is clicked", Toast.LENGTH_SHORT)
toast?.show()
}

Kotlin getString in another Activity / Function

when I use this code, my recycler view app crashed because I got an null object reference exception bt at the moment I did not know how to fix it. I tried to softcode the strings in my view text but it does not work. When I hardcoded it, it works :(
The issue is in the line of
mContext.getString(R.string.strClick)
Here is my code:
package de.reuter.myapplication
import android.content.Context
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.LinearLayoutManager
import de.reuter.timetable.RecycleAdapter
import kotlinx.android.synthetic.main.activity_content_backend.*
class BackendContentActivity : AppCompatActivity()
{
val mContext: Context = this
private val exampleList = generateDummyList(5, this)
private val adapter = RecycleAdapter(exampleList, mContext)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_content_backend)
recycler_view.adapter = adapter
recycler_view.layoutManager = LinearLayoutManager(this)
recycler_view.setHasFixedSize(true)
}
private fun generateDummyList(size: Int, mContext: Context): ArrayList<AdapterItems> {
val list = ArrayList<AdapterItems>()
var drawable: Int
var txt0: String
var txt1: String
var txt2: String = mContext.getString(R.string.strClick)
for (i in 0 until size) {
when (i % 5) {
0 -> {
drawable = R.drawable.bg_circle_blue
txt0 = "M"
txt1 = "Monday"
}
1 -> {
drawable = R.drawable.bg_circle_green
txt0 = "T"
txt1 = "Tuesday"
}
2 -> {
drawable = R.drawable.bg_circle_red
txt0 = "W"
txt1 = "Wednesay"
}
3 -> {
drawable = R.drawable.bg_circle_yellow
txt0 = "T"
txt1 = "Thursday"
}
4 -> {
drawable = R.drawable.bg_circle_purple
txt0 = "F"
txt1 = "Friday"
}
else -> {
drawable = R.drawable.bg_circle_purple
txt0 = "W"
txt1 = "Wrong"
}
}
var item = AdapterItems(drawable, txt0, txt1, txt2)
list += item
}
return list
}
}
My Recycler Adapter:
package de.reuter.timetable
import android.content.Context
import android.content.Intent
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageView
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import com.google.android.material.snackbar.Snackbar
import de.reuter.myapplication.AdapterItems
import de.reuter.myapplication.MondayActivity
import de.reuter.myapplication.R
import kotlinx.android.synthetic.main.card_layout.view.*
class RecycleAdapter(private val exampleList: List<AdapterItems>, context: Context) :
RecyclerView.Adapter<RecycleAdapter.ExampleViewHolder>() {
var mContext = context
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ExampleViewHolder {
val itemView = LayoutInflater.from(parent.context).inflate(
R.layout.card_layout,
parent, false
)
return ExampleViewHolder(itemView)
}
override fun onBindViewHolder(holder: ExampleViewHolder, position: Int) {
val currentItem = exampleList[position]
holder.imageView.setImageResource(currentItem.imageResource)
holder.textView0.text = currentItem.text1
holder.textView1.text = currentItem.text2
holder.textView2.text = currentItem.text3
}
override fun getItemCount() = exampleList.size
inner class ExampleViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
var imageView: ImageView = itemView.image_view
var textView0: TextView = itemView.txtShortLetterM
var textView1: TextView = itemView.txtViewMonday
var textView2: TextView = itemView.txtClickLink
init {
imageView = itemView.findViewById(R.id.image_view)
textView0 = itemView.findViewById(R.id.txtShortLetterM)
textView1 = itemView.findViewById(R.id.txtViewMonday)
textView2 = itemView.findViewById(R.id.txtClickLink)
itemView.setOnClickListener { v: View ->
var position: Int = getAdapterPosition()
var text: String
when (position) {
0 -> {
var intent = Intent(mContext, MondayActivity::class.java)
mContext.startActivity(intent)
}
else -> {
text = "Click detected on item $position"
Snackbar.make(
v, text,
Snackbar.LENGTH_LONG
).setAction("Action", null).show()
}
}
}
}
}
}
Thank you very much for helping

Try to move generateDummyList(5, this) call to onCreate method of BackendContentActivity class:
class BackendContentActivity : AppCompatActivity() {
private lateinit var exampleList: ArrayList<AdapterItems>
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_content_backend)
exampleList = generateDummyList(5, this)
// ...
}
// ...
}