Develop Reference

Getting Error in building the project using Dao interface and room library

I am stuck with this issue since couple of days. I have gone through many threads where people faced similar issues but did not find any work around on this.
Im getting the error because of using suspend in dao interface but when i remove the error goes away but the app crashes when i try to open it after installation.
I have tried changing the version of room in gradle but that didnot work either.
have a look at my code.
The error message
kotlin.coroutines.Continuation<? super kotlin.Unit> continuation);
NotesDao.kt
package com.example.notes
import androidx.lifecycle.LiveData
import androidx.room.*
#Dao
interface NoteDao {
#Insert(onConflict = OnConflictStrategy.IGNORE)
suspend fun insert(note : Note)
#Delete
suspend fun delete(note : Note)
#Query("Select * from notes_table order by id ASC")
fun getAllNotes() : LiveData <List<Note>>
}
NotesRCAdapter.kt
package com.example.notes
import android.content.Context
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
class NotesRVAdapter(private val context: Context, private val listner : INotesRVAdapter)
: RecyclerView.Adapter<NotesRVAdapter.NoteViewHolder>() {
val allNotes = arrayListOf<Note>()
class NoteViewHolder (itemview : View) : RecyclerView.ViewHolder(itemview){
val textView = itemView.findViewById<TextView>(R.id.tvNote)
val deleteButton = itemview.findViewById<ImageView>(R.id.ivDelete)
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): NoteViewHolder {
val viewHolder = NoteViewHolder( LayoutInflater.from(context)
.inflate(R.layout.item_note, parent, false))
viewHolder.deleteButton.setOnClickListener{
listner.onItemClicked(allNotes[viewHolder.adapterPosition])
}
return viewHolder
}
override fun onBindViewHolder(holder: NoteViewHolder, position: Int) {
val currentNote = allNotes[position]
holder.textView.text = currentNote.text
}
override fun getItemCount(): Int {
return allNotes.size
}
fun updateList(newList : List<Note>){
allNotes.clear()
allNotes.addAll(newList)
notifyDataSetChanged()
}
}
interface INotesRVAdapter{
fun onItemClicked(note: Note)
}
NotesDataBase.kt
package com.example.notes
import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase
#Database(entities = [Note::class], version = 1, exportSchema = false)
abstract class NoteDataBase: RoomDatabase() {
abstract fun getNoteDao(): NoteDao
companion object {
// Singleton prevents multiple instances of database opening at the
// same time.
#Volatile
private var INSTANCE: NoteDataBase? = null
fun getDatabase(context: Context): NoteDataBase {
// if the INSTANCE is not null, then return it,
// if it is, then create the database
return INSTANCE ?: synchronized(this) {
val instance = Room.databaseBuilder(
context.applicationContext,
NoteDataBase::class.java,
"note_database"
).build()
INSTANCE = instance
// return instance
instance
}
}
}
}
//after this we will create our repository
NotesRepository.kt
package com.example.notes
import androidx.lifecycle.LiveData
class NoteRepository(private val noteDao: NoteDao) {
val allNotes : LiveData<List<Note>> = noteDao.getAllNotes()
suspend fun insert(note: Note) {
noteDao.insert(note)
}
suspend fun delete(note: Note){
noteDao.delete(note)
}
}
NoteViewModel.kt
package com.example.notes
import android.app.Application
import androidx.lifecycle.AndroidViewModel
import androidx.lifecycle.LiveData
import androidx.lifecycle.viewModelScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.launch
class NoteViewModel(application: Application) : AndroidViewModel(application){
private val repository : NoteRepository
val allNotes : LiveData<List<Note>>
init {
val dao = NoteDataBase.getDatabase(application).getNoteDao()
repository = NoteRepository(dao)
allNotes = repository.allNotes
}
fun deleteNote(note: Note) = viewModelScope.launch(Dispatchers.IO) {
repository.delete(note)
}
fun insertNote(note: Note) = viewModelScope.launch(Dispatchers.IO) {
repository.insert(note)
}
}
Note.kt
package com.example.notes
import androidx.room.ColumnInfo
import androidx.room.Entity
import androidx.room.PrimaryKey
#Entity(tableName = "notes_table") /
class Note(#ColumnInfo(name = "text")val text: String) {
#PrimaryKey(autoGenerate = true) var id = 0
}
MainActivity.kt
package com.example.notes
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.EditText
import android.widget.Toast
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModel
import androidx.lifecycle.ViewModelProvider
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
class MainActivity : AppCompatActivity(), INotesRVAdapter {
lateinit var viewModel: NoteViewModel
private val input = findViewById<EditText>(R.id.etInput)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val RecyclerView = findViewById<RecyclerView>(R.id.recyclerView)
RecyclerView.layoutManager = LinearLayoutManager(this)
val adapter = NotesRVAdapter(this, this)
RecyclerView.adapter = adapter
viewModel = ViewModelProvider(this,
ViewModelProvider.AndroidViewModelFactory.getInstance(application))
.get(NoteViewModel::class.java)
viewModel.allNotes.observe(this, Observer { list ->
list?.let {
adapter.updateList(it)
}
})
}
override fun onItemClicked(note: Note) {
viewModel.deleteNote(note)
Toast.makeText(this,"${note.text} Deleted", Toast.LENGTH_LONG).show()
}
fun submitData(view: View) {
val noteText = input.text.toString()
if (noteText.isNotEmpty()){
viewModel.insertNote(Note(noteText))
Toast.makeText(this,"$noteText Inserted", Toast.LENGTH_LONG).show()
}
}
}
immediate help will be appreciated in understanding the issue and where I went wrong.
Thanks.

Try changing class of entity to data class and also the id field
package com.example.notes
import androidx.room.ColumnInfo
import androidx.room.Entity
import androidx.room.PrimaryKey
#Entity(tableName = "notes_table")
data class Note(
#ColumnInfo(name = "text")val text:
String),
#PrimaryKey(autoGenerate = true)
#ColumnInfo(name = "text_id")
var id = 0)

RecyclerView: No adapter attached; skipping layout - kotlin

I know this problem has been posted but all seemed to be posted in java code. I'm just trying to implement a small example recyclerView. Not sure what I'm doing incorrect, any insight would be great, TIA.
MainActivity.kt
package com.wildcardev.androidtest1
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import androidx.recyclerview.widget.LinearLayoutManager
import com.wildcardev.androidtest1.adapters.RecyclerAdapter
import com.wildcardev.androidtest1.databinding.ActivityMainBinding
import com.wildcardev.androidtest1.models.TestDataObj
fun addDataToList(arrayList:ArrayList<TestDataObj>): ArrayList<TestDataObj>{
arrayList.add(TestDataObj("tes1", "test2", "test3"))
arrayList.add(TestDataObj("test2", "testt2", "testt2"))
arrayList.add(TestDataObj("tes12", "test22", "test32"))
arrayList.add(TestDataObj("tes13", "test23", "test33"))
arrayList.add(TestDataObj("tes14", "test24", "test34"))
arrayList.add(TestDataObj("tes15", "test25", "test35"))
return arrayList
}
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
val testList: ArrayList<TestDataObj> = ArrayList()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(R.layout.activity_main)
val list = addDataToList(testList)
Log.d("TEST1","$list")
Log.d("TEST1","${binding.recyclerView}")
binding.recyclerView.layoutManager = LinearLayoutManager(this#MainActivity)
val adapter = RecyclerAdapter(list)
binding.recyclerView.adapter = adapter
}
}
TestDataObj.kt
package com.wildcardev.androidtest1.models
data class TestDataObj(
val title: String,
val description: String,
val date: String
)
RecyclerAdapter.kt
package com.wildcardev.androidtest1.adapters
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import com.wildcardev.androidtest1.R
import com.wildcardev.androidtest1.models.TestDataObj
class RecyclerViewHolder(view: View): RecyclerView.ViewHolder(view){
var title: TextView = view.findViewById(R.id.title)
var description: TextView = view.findViewById(R.id.description)
var date: TextView = view.findViewById(R.id.date)
}
class RecyclerAdapter(private var list: ArrayList<TestDataObj>): RecyclerView.Adapter<RecyclerViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerViewHolder {
Log.d("onCreateView", "INHOLDERcreate")
val view = LayoutInflater.from(parent.context).inflate(R.layout.activity_main, parent, false)
return RecyclerViewHolder(view)
}
override fun onBindViewHolder(holder: RecyclerViewHolder, position: Int) {
Log.d("ADAPTER", "INBINDfunc")
val item = list[position]
holder.title.text = item.title
holder.description.text = item.description
holder.date.text = item.date
}
override fun getItemCount(): Int {
Log.d("COUNT",".getItemCountcalled")
return list.size
}
}

Try
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)

I fixed my issue. When using viewBinding/dataBinding, you need to pass dataBinding to the viewHolder. Unfortunately I did not get this as I was just following tutorials that are using synthetic imports. So I changed my Adapter code to the following
RecyclerAdapter.kt
package com.wildcardev.androidtest1.adapters
import android.util.Log
import android.view.LayoutInflater
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import com.wildcardev.androidtest1.models.TestDataObj
import com.wildcardev.androidtest1.databinding.ListItemBinding
class RecyclerViewHolder(viewDataBinding: ListItemBinding): RecyclerView.ViewHolder(viewDataBinding.root){
var title: TextView? = viewDataBinding.title
var description: TextView? = viewDataBinding.description
var date: TextView? = viewDataBinding.date
}
class RecyclerAdapter(private var list: ArrayList<TestDataObj>): RecyclerView.Adapter<RecyclerViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerViewHolder {
Log.d("onCreateView", "INHOLDERcreate")
val binding = ListItemBinding.inflate(LayoutInflater.from(parent.context),parent,false)
return RecyclerViewHolder(binding)
}
override fun onBindViewHolder(holder: RecyclerViewHolder, position: Int) {
Log.d("ADAPTER", "INBINDfunc $holder")
val item = list[position]
holder.title?.text = item.title
holder.description?.text = item.description
holder.date?.text = item.date
}
override fun getItemCount(): Int {
Log.d("COUNT",".getItemCountcalled ${list.size}")
return list.size
}
}

Recycler view data not loading on screen

I'm trying to show the recycler view's data on my app. The thing is, even though the NetworkStatus is successful (I can tell because I don't get the toast's message and the loader disappears and I can also see the data in the logcat), the info is not displayed. I am not sure if the error is in the way I'm calling the recycler view on my MainActivity or in the RecyclerAdapter but any idea as to where the problem is would be very helpful.
This is the RecyclerAdapter:
import android.view.LayoutInflater
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import com.app.mortyapp.databinding.ItemDetailBinding
class RecyclerAdapter(private var characterList: List<Character>): RecyclerView.Adapter<RecyclerAdapter.ViewHolder>() {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerAdapter.ViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
val binding = ItemDetailBinding.inflate(
layoutInflater,
parent,
false
)
return ViewHolder(binding)
}
override fun getItemCount(): Int = characterList.size
override fun onBindViewHolder(holder: RecyclerAdapter.ViewHolder, position: Int) {
holder.bind(characterList[position])
}
fun setCharacterList(characterList: List<Character>){
this.characterList = characterList
notifyDataSetChanged()
}
inner class ViewHolder(
private val binding: ItemDetailBinding
) : RecyclerView.ViewHolder(binding.root){
fun bind(character: Character) {
with(binding){
val itemName: TextView = binding.tvName
val itemGender: TextView = binding.tvGender
itemName.text = character.name
itemGender.text = character.gender
}
}
}
}
This is the MainActivity:
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.View
import android.widget.ProgressBar
import android.widget.Toast
import androidx.activity.viewModels
import androidx.lifecycle.Observer
import androidx.recyclerview.widget.LinearLayoutManager
import com.app.mortyapp.databinding.ActivityMainBinding
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private val characters = mutableListOf<Character>()
private lateinit var progressBar: ProgressBar
private lateinit var recyclerAdapter: RecyclerAdapter
private val viewModel: MainViewModel by viewModels(
factoryProducer = {MainViewModelFactory()}
)
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
progressBar = binding.ProgressBar
progressBar.visibility = View.INVISIBLE
setObservers()
initRecyclerView()
}
private fun initRecyclerView() {
with(binding.rvCharacters){
layoutManager = LinearLayoutManager(context)
recyclerAdapter = RecyclerAdapter(characters).apply {
setCharacterList(characters)
}
}
}
private fun setObservers(){
viewModel.characterList.observe(this, Observer {
when(it.status){
NetworkStatus.LOADING ->{
//show loading state
progressBar.visibility = View.VISIBLE
}
NetworkStatus.SUCCESS -> {
//hide loading state
progressBar.visibility = View.INVISIBLE
//render character list
recyclerAdapter.setCharacterList(characters)
}
NetworkStatus.ERROR -> {
//show error message
Toast.makeText(this,"Error loading content", Toast.LENGTH_SHORT).show()
//hide loading state
progressBar.visibility = View.INVISIBLE
}
}
})
}
}
API response:
import com.google.gson.annotations.SerializedName
data class Character (
#SerializedName("id") val id: Int,
#SerializedName("name") val name: String,
#SerializedName("gender") val gender: String
)
data class CharacterListResponse(
#SerializedName("results") val results: List<Character>
)
Remote data source:
package com.app.mortyapp
import com.app.mortyapp.Model.CharacterService
import com.app.mortyapp.Model.RetrofitServices
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response
class CharacterRemoteDataSource {
fun getCharacterList(networkResponse: NetworkResponse<List<Character>>) {
val service = RetrofitServices.instance
.create(CharacterService::class.java)
.getCharacterList()
service.enqueue(object : Callback<CharacterListResponse> {
override fun onResponse(
call: Call<CharacterListResponse>,
response: Response<CharacterListResponse>
) {
val resource = response.body()?.run {
if (results.isNotEmpty())
Resource(NetworkStatus.SUCCESS, results)
else
Resource(NetworkStatus.ERROR)
} ?: run {
Resource(NetworkStatus.ERROR)
}
networkResponse.onResponse(resource)
}
override fun onFailure(call: Call<CharacterListResponse>, t: Throwable) {
networkResponse.onResponse(Resource(NetworkStatus.ERROR, message = t.message))
}
})
}
}
interface NetworkResponse<T> {
fun onResponse(value: Resource<T>)
}

Set adapter for Recyclerview in
setupRecylerview ()
adapter = recyclerAdapter
NetworkStatus.SUCCESS -> {
//hide loading state
progressBar.visibility = View.INVISIBLE
//render character list
recyclerAdapter.setCharacterList(characters)
recyclerAdapter.notifydatasetchanged()//add this line
}

I think most problems found with recyclerView isn't linked to it, but with some adjourning codes. For example, a very similar problem was solved by finding out that the adapter POJO class was retrieving 0 rather than the actual size of the array list.
See the solved problem here:
Android Recycler View not loading Data (Peculiar problem, Not a Duplicate)

intent.putExtra: None of the following functions can be called with the arguments supplied

I'm trying to pass data from one activity to another through an intent with putExtra. The thing is, I get the error that says: None of the following functions can be called with the arguments supplied.
I'm not sure why it's not working, since the variable that I'm referencing is in the viewholder. Any clue as to what's going on and how to fix it would help a lot.
This is my recycler adapter:
package com.example.newsapp
import android.content.Intent
import android.icu.text.CaseMap
import android.net.Uri
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.AdapterView
import android.widget.ImageView
import android.widget.TextView
import androidx.core.content.ContextCompat.startActivity
import androidx.recyclerview.widget.RecyclerView
import com.example.newsapp.databinding.NewsItemBinding
import com.squareup.picasso.Picasso
class RecyclerAdapter (
private var Titles: List<String>,
private var Images: List<String>,
private var Authors: List<String>,
private var Descriptions: List<String>
) : RecyclerView.Adapter<RecyclerAdapter.ViewHolder>(){
inner class ViewHolder(
view: View
): RecyclerView.ViewHolder(view){
private val binding = NewsItemBinding.bind(view)
val itemTitle: TextView = binding.tvTitle
val itemImage: ImageView = binding.ivNewsImage
fun bind(urlToImage:String){
Picasso.get().load(urlToImage).into(binding.ivNewsImage)
}
init {
itemImage.setOnClickListener{
val intent = Intent(view.context, PostActivity::class.java)
intent.putExtra("title",itemTitle)
view.context.startActivity(intent)
}
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val v = LayoutInflater.from(parent.context).inflate(R.layout.news_item, parent, false)
return ViewHolder(v)
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.itemTitle.text = Titles[position]
val itemImage = Images[position]
holder.bind(itemImage)
}
override fun getItemCount(): Int {
return Titles.size
}
}
The part with the issue is this one:
init {
itemImage.setOnClickListener{
val intent = Intent(view.context, PostActivity::class.java)
intent.putExtra("title",itemTitle) view.context.startActivity(intent)
}
}
This is my main activity:
package com.example.newsapp
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.newsapp.databinding.ActivityMainBinding
import kotlinx.coroutines.*
import retrofit2.Retrofit
import retrofit2.converter.gson.GsonConverterFactory
import java.lang.Exception
class MainActivity : AppCompatActivity() {
private lateinit var binding: ActivityMainBinding
private lateinit var adapter: RecyclerAdapter
private val newsTitles = mutableListOf<String>()
private val newsImages = mutableListOf<String>()
private val newsAuthors = mutableListOf<String>()
private val newsDescriptions = mutableListOf<String>()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
binding = ActivityMainBinding.inflate(layoutInflater)
setContentView(binding.root)
makeAPIRequest()
}
private fun initRecyclerView() {
adapter = RecyclerAdapter( newsTitles, newsImages)
binding.rvNews.layoutManager = LinearLayoutManager(this)
binding.rvNews.adapter = adapter
}
private fun addToList(title:String, image:String, author:String, description:String){
newsTitles.add(title)
newsImages.add(image)
newsAuthors.add(author)
newsDescriptions.add(description)
}
private fun makeAPIRequest() {
val api = Retrofit.Builder()
.baseUrl("https://newsapi.org/")
.addConverterFactory(GsonConverterFactory.create())
.build()
.create(APIService::class.java)
GlobalScope.launch(Dispatchers.IO){
val response = api.getNews()
val posts = response.body()
try{
if (posts != null) {
for(art in posts.Articles){
Log.i("Main Activity", "Result = $art")
addToList(art.Title,art.urlToImage, art.Author, art.Description)
}
}
withContext(Dispatchers.Main){
initRecyclerView()
}
} catch (e:Exception){
Log.e("Main Activity", e.toString())
}
}
}
}

intent.putExtra("title",itemTitle)
Here, itemTitle is a TextView. You cannot pass a TextView between activities. You could switch to:
intent.putExtra("title",itemTitle.text)
...to put the text from the TextView into the extra.
Also, you might want to consider whether these should be separate activities or just two fragments (or composables) in a single activity.

ViewHolder with onClicklistener Issue with UninitializedPropertyAccessException

I'm a beginner so please bare with me.
I have a viewholder that has an onclicklistener.
The aim of the click is to send a Url string into another fragment using Jetpack Navigation (hopefully i did it right)
the Url is being created within the dataclass itself.
but i keep getting this error:
kotlin.UninitializedPropertyAccessException: lateinit property galleryItem has not been initialized
I tried working around using companion object and other ways, nothing worked... is there a solution for this?
here is the view holder and data class
import android.annotation.SuppressLint
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.ImageButton
import androidx.core.os.bundleOf
import androidx.navigation.Navigation
import androidx.paging.PagingDataAdapter
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.RecyclerView
import com.bumptech.glide.Glide
import com.saheralsous.android.R
import com.saheralsous.android.database.remote.model.PagingData
class RecyclerViewPhotoAdapter() :
PagingDataAdapter<PagingData.GalleryItem, PhotoHolder>(
diffCallback = DiffCallback
) {
override fun onBindViewHolder(holder: PhotoHolder, position: Int) {
getItem(position)?.let {
holder.bind(it)
}
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): PhotoHolder {
val view = LayoutInflater.from(parent.context).inflate(R.layout.photo_item_view,parent,false)
return PhotoHolder(view)
}
}
class PhotoHolder(view: View):
RecyclerView.ViewHolder(view), View.OnClickListener {
private val imageButtom: ImageButton = view.findViewById(R.id.ImageButton)
private lateinit var galleryItem: PagingData.GalleryItem //page. 594
#SuppressLint("ResourceType")
fun bind(galleryItem : PagingData.GalleryItem){
/*
idTextView.text = galleryItem.id
ownerTextView.text = galleryItem.owner
titleTextView.text = galleryItem.title
urlTextView.text = galleryItem.url
*/
galleryItem.url.let { url ->
Glide.with(itemView)
.load(url)
.override(350,350)
.into(imageButtom)
}
}
init {
imageButtom.setOnClickListener(this)
}
override fun onClick(v: View?) {
println("item was clicked")
val bundle = bundleOf("url" to galleryItem.photoPageUri ) <-- here is the issue
Navigation.findNavController(v!!).navigate(
R.id.action_photoGalleryFragment_to_photoPageFragment,
bundle)
}
}
object DiffCallback : DiffUtil.ItemCallback<PagingData.GalleryItem>() {
override fun areItemsTheSame(oldItem: PagingData.GalleryItem, newItem: PagingData.GalleryItem): Boolean {
// Id is unique.
return oldItem.id == newItem.id
}
override fun areContentsTheSame(oldItem: PagingData.GalleryItem, newItem: PagingData.GalleryItem): Boolean {
return oldItem == newItem
}
}
data class
import android.net.Uri
import androidx.annotation.Keep
import com.google.gson.annotations.SerializedName
data class PagingData(
val total : Int =0,
val Page: Int = 0,
val photos : List<GalleryItem>
){
val endOfPage = total == Page
#Keep
data class GalleryItem(
#SerializedName("id")
val id: String,
#SerializedName("owner")
val owner: String,
#SerializedName("title")
var title: String,
#SerializedName("url_s")
val url: String) {
val photoPageUri : Uri <-- here is the value
get() {
return Uri.parse("https://www.flickr.com/photos/")
.buildUpon()
.appendPath(owner)
.appendPath(id)
.build()
}
}
}

As the error states, you haven't initialised the galleryItem instance variable in your PhotoHolder. Add this inside your bind method:
this.galleryItem = galleryItem