Develop Reference

How use View.OnClickListener with FirestoreRecyclerAdapter

I'm trying to create an application and considering my level it's not easy! I hope you could help me since I didn't succeed with the many links I found on the internet.
I can't add the onClick function of View.OnClickListener, each time the Intent function is not recognized. I tried to implement it in the UserViewHolder and FirestoreRecyclerAdapter class but it doesn't work.
Here is my current code:
---------- kotlin part ---------
package edu.stanford.rkpandey.emojistatus
import android.content.Intent
import android.os.Bundle
import android.util.Log
import android.view.*
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.firebase.ui.firestore.FirestoreRecyclerAdapter
import com.firebase.ui.firestore.FirestoreRecyclerOptions
import com.google.firebase.auth.FirebaseAuth
import com.google.firebase.auth.ktx.auth
import com.google.firebase.firestore.ktx.firestore
import com.google.firebase.ktx.Firebase
import kotlinx.android.synthetic.main.activity_main.*
data class User(
val displayName: String? = "",
val emojis: String? = ""
)
class UserViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView)
class MainActivity : AppCompatActivity() {
private val db = Firebase.firestore
private lateinit var auth: FirebaseAuth
// Query the users collection
private val query = db.collection("users")
val options = FirestoreRecyclerOptions.Builder<User>()
.setQuery(query, User::class.java)
.setLifecycleOwner(this).build()
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
auth = Firebase.auth
val adapter = object: FirestoreRecyclerAdapter<User, UserViewHolder>(options) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): UserViewHolder {
val view = LayoutInflater.from(this#MainActivity).inflate(R.layout.item_pack, parent, false)
return UserViewHolder(view)
}
override fun onBindViewHolder(
holder: UserViewHolder,
position: Int,
model: User
) {
val tvName: TextView = holder.itemView.findViewById(R.id.title)
val tvEmojis: TextView = holder.itemView.findViewById(R.id.excerpt)
tvName.text = model.displayName
tvEmojis.text = model.emojis
}
}
rvUsers.adapter = adapter
rvUsers.layoutManager = LinearLayoutManager(this)
}
override fun onCreateOptionsMenu(menu: Menu?): Boolean {
menuInflater.inflate(R.menu.menu_main, menu)
return true
}
override fun onOptionsItemSelected(item: MenuItem): Boolean {
if (item.itemId == R.id.miLogout) {
Log.i("MainActivity", "Logout")
auth.signOut()
val logoutIntent = Intent(this, LoginActivity::class.java)
logoutIntent.flags = Intent.FLAG_ACTIVITY_NEW_TASK or Intent.FLAG_ACTIVITY_CLEAR_TASK
startActivity(logoutIntent)
}
return super.onOptionsItemSelected(item)
}
}
------- xml part -------
=> activity_main
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".MainActivity">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rvUsers"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
=> item_pack
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="100sp"
xmlns:app="http://schemas.android.com/apk/res-auto">
<androidx.cardview.widget.CardView
android:id="#+id/card_view"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginStart="12sp"
android:layout_marginTop="12sp"
android:layout_marginEnd="12sp"
android:focusable="true"
android:clickable="true"
app:cardCornerRadius="10dp"
android:foreground="?android:attr/selectableItemBackground">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:padding="10dp"
android:background="#color/colorPack">
<TextView
android:id="#+id/title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="5sp"
style="#style/NoteTitleFont"
android:textColor="#color/colorTitle"
tools:text="Note 1" />
<TextView
android:id="#+id/excerpt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="12sp"
android:layout_below="#id/title"
android:maxLines="1"
android:ellipsize="end"
android:textStyle="italic"
android:textColor="#color/colorDescribe"
tools:text="test text va se trouver ici, ça va contenir le début de la description du package." />
</RelativeLayout>
</androidx.cardview.widget.CardView>
</RelativeLayout>
This code gives this result :
I would like that when I click on one of the carviews it can go to the activity_pack_detail.
Do you know how to do Intent to PackDetailActivity?
I get this error no matter what I do =>

You're getting that error because you are calling Intent's class constructor with a wrong argument. The first argument should be a Context and not a View. The keyword this is referring in your code to a View and not to a context, hence the error.
To solve this, you have to pass a Context object like this:
val i = Intent(view.getContext(), PackDetailActivity::class.java)
And your error will go away.

RecyclerView functions aren't called

I am trying to show a list of transactions in a recycler view.
Each transaction is represented by a CardView inside a constraint layout (see item_transaction.xml).
Somehow, the functions of my RecyclerView Adapter (onCreateViewHolder, onBindViewHolder and getItemCount) are never called (logs are never displayed - I removed most of them so the code is easier to read).
Therefore, the RecyclerView content doesn't display on my app.
It is also worth pointing out that I have a list of transactions called data in my adapter. Whenever I set the data in the list, it does update. No issues there.
💡 I know notifyDataSetChanged() isn't clean, I'll change it later on when I manage to get everything working.
Here is a preview of what I want so you can grasp the idea better :
EDIT : My fragment displays normally and has no problem executing code.
Hang on tight because there is a lot of code :
package com.example.manage.manageit.database
class Transaction(
var value: Long = 0,
var note: String = "",
var budget: String = "",
var creationTime: Long = System.currentTimeMillis()
)
Transaction.kt
package com.example.manage.manageit.home
import android.os.Bundle
import androidx.appcompat.app.AppCompatActivity
import androidx.databinding.DataBindingUtil
import com.example.manage.manageit.databinding.ActivityHomeBinding
import androidx.fragment.app.Fragment
import com.example.manage.manageit.R
import com.example.manage.manageit.about.AboutFragment
import com.example.manage.manageit.budget.TransactionFragment
class HomeActivity : AppCompatActivity() {
private lateinit var binding: ActivityHomeBinding
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
binding = DataBindingUtil.setContentView(this, R.layout.activity_home)
binding.bottomNavigation.menu.getItem(0).isCheckable = true
setFragment(HomeFragment())
binding.bottomNavigation.setOnItemSelectedListener {menu ->
when(menu.itemId){
R.id.homeFragmentButton -> {
setFragment(HomeFragment())
true
}
R.id.transactionFragmentButton -> {
setFragment(TransactionFragment())
true
}
R.id.aboutFragmentButton -> {
setFragment(AboutFragment())
true
}
else -> false
}
}
}
private fun setFragment(fr : Fragment){
val frag = supportFragmentManager.beginTransaction()
frag.replace(R.id.myNavHostFragment,fr)
frag.commit()
}
}
HomeActivity.kt : It contains a BottomNavigationView and my fragment.
package com.example.manage.manageit.home
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.databinding.DataBindingUtil
import androidx.fragment.app.Fragment
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import com.example.manage.manageit.R
import com.example.manage.manageit.adapters.TransactionAdapter
import com.example.manage.manageit.database.Transaction
import com.example.manage.manageit.databinding.FragmentHomeBinding
import java.util.logging.Logger
class HomeFragment : Fragment() {
private var logger = Logger.getLogger(HomeFragment::class.java.name)
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val binding: FragmentHomeBinding = DataBindingUtil.inflate(
inflater,
R.layout.fragment_home,
container,
false
)
val recyclerView: RecyclerView = binding.transactionList
val transactionAdapter = TransactionAdapter()
recyclerView.adapter = transactionAdapter
recyclerView.layoutManager = LinearLayoutManager(context)
transactionAdapter.data = listOf(
Transaction(10, "Transaction note", "Groceries"),
Transaction(20, "Transaction note", "Groceries"),
Transaction(30, "Transaction note", "Groceries")
)
return inflater.inflate(R.layout.fragment_home, container, false)
}
}
HomeFragment.kt
package com.example.manage.manageit.adapters
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.example.manage.manageit.R
import com.example.manage.manageit.database.Transaction
import java.util.logging.Logger
class TransactionAdapter : RecyclerView.Adapter<TransactionViewHolder>() {
private var logger = Logger.getLogger(this::class.java.name)
var data = listOf<Transaction>()
set(value) {
field = value
notifyDataSetChanged()
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): TransactionViewHolder {
logger.info("adapter : onCreateViewHolder()")
return TransactionViewHolder.from(parent)
}
override fun onBindViewHolder(holder: TransactionViewHolder, position: Int) {
val item = this.data[position]
holder.bind(item)
}
override fun getItemCount(): Int {
logger.info("adapter : getItemCount()")
return this.data.size
}
}
class TransactionViewHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
private val icon: ImageView = itemView.findViewById(R.id.transaction_icon)
private val note: TextView = itemView.findViewById(R.id.transaction_note)
private val value: TextView = itemView.findViewById(R.id.transaction_value)
fun bind(item: Transaction) {
icon.setImageResource(R.drawable.ic_dollar_sign)
note.text = item.note
value.text = item.value.toString()
}
companion object {
fun from(parent: ViewGroup): TransactionViewHolder {
val layoutInflater = LayoutInflater.from(parent.context)
val view = layoutInflater
.inflate(R.layout.item_transaction, parent, false)
return TransactionViewHolder(view)
}
}
}
TransactionAdapter.kt
<?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"
tools:context="com.example.manage.manageit.home.HomeActivity">
<RelativeLayout
android:id="#+id/container"
android:layout_width="match_parent"
android:layout_height="match_parent">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<androidx.fragment.app.FragmentContainerView
android:id="#+id/myNavHostFragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"/>
</LinearLayout>
<com.google.android.material.bottomnavigation.BottomNavigationView
android:id="#+id/bottom_navigation"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:background="#android:color/black"
android:paddingVertical="6dp"
app:itemIconSize="28dp"
app:itemIconTint="#color/nav_bar_item"
app:itemRippleColor="#color/ripple_color"
app:itemTextColor="#color/nav_bar_item"
app:labelVisibilityMode="unlabeled"
app:menu="#menu/bottom_navigation_menu" />
</RelativeLayout>
</layout>
activity_home.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"
xmlns:tools="http://schemas.android.com/tools">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:background="#android:color/black"
android:fillViewport="true"
tools:context="com.example.manage.manageit.home.HomeFragment">
<TextView
android:id="#+id/homeActivityTitle"
style="#style/activityTitle"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="#dimen/medium_margin"
android:layout_marginTop="#dimen/medium_margin"
android:layout_marginEnd="#dimen/medium_margin"
android:text="#string/home_text"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/transaction_list"
android:layout_width="match_parent"
android:layout_height="400dp"
android:visibility="visible"
app:layout_constraintBottom_toTopOf="#+id/floatingActionButton"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/homeActivityTitle" />
<com.google.android.material.floatingactionbutton.FloatingActionButton
android:id="#+id/floatingActionButton"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="#dimen/medium_margin"
android:layout_marginBottom="#dimen/very_big_margin"
android:backgroundTint="#color/secondaryColor"
android:clickable="true"
android:contentDescription="#string/add_button_description"
android:src="#drawable/ic_plus"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:maxImageSize="32dp"
tools:ignore="RedundantDescriptionCheck" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
fragment_home.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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"
android:layout_width="match_parent"
android:layout_height="wrap_content">
<androidx.cardview.widget.CardView
android:layout_width="0dp"
android:layout_height="wrap_content"
android:layout_marginStart="20dp"
android:layout_marginTop="20dp"
android:layout_marginEnd="20dp"
app:cardBackgroundColor="#android:color/transparent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="60dp"
android:background="#drawable/transaction">
<ImageView
android:id="#+id/transaction_icon"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="30dp"
android:contentDescription="Icon"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:srcCompat="#drawable/ic_dollar_sign"
app:tint="#android:color/white" />
<TextView
android:id="#+id/transaction_note"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginStart="30dp"
android:text="Transaction note"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toEndOf="#+id/transaction_icon"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/transaction_value"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginEnd="30dp"
android:text="55€"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
</androidx.constraintlayout.widget.ConstraintLayout>
item_transaction.xml : Basically a card view with an image and two text views (the transaction "note" and value).

In onCreateView, you have created your view layout twice. The first one you did using DataBindingUtil and that's the one whose RecyclerView you set up. But then you let that whole layout go back to the garbage collector because you create a brand new layout using layoutInflater and return that layout on the last line of onCreateView.
Technically, you should not be setting up views in onCreateView anyway. It should be done in onViewCreated(), although I don't think it makes much difference. However, since Fragment provides a constructor that can automatically inflate a provided layout ID, I think it's cleaner anyway to eliminate onCreateView() entirely, like this:
class HomeFragment : Fragment(R.layout.fragment_home) {
private var logger = Logger.getLogger(HomeFragment::class.java.name)
override fun onViewCreated(
view: View,
savedInstanceState: Bundle?
) {
val binding: FragmentHomeBinding = DataBindingUtil.bind(view)
val recyclerView: RecyclerView = binding.transactionList
val transactionAdapter = TransactionAdapter()
recyclerView.adapter = transactionAdapter
recyclerView.layoutManager = LinearLayoutManager(context)
transactionAdapter.data = listOf(
Transaction(10, "Transaction note", "Groceries"),
Transaction(20, "Transaction note", "Groceries"),
Transaction(30, "Transaction note", "Groceries")
)
}
}

(Android Kotlin) RecyclerView Adapter methods not called: empty RecyclerView being shown

I am trying to display JSON data from a dummy server (json-server) using Retrofit2 and display it in a RecyclerView placed inside a fragment. So far the following events are taking place (found out using Log infos):
Main fragment CharactersListFragment.kt creation is initiated.
Only getItemCount() is being called. It is returning 0.
OnCreateViewHolder() and onBindViewHolder() are not being called.
Data is successfully fetched from the server and passed to the adapter (from CharactersListFragment.kt)
There are no compile time errors nor does my app crash, just the RecyclerView is empty.
Here are my code files:
Layout for fragment with RecyclerView: fragment_characters_list.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto"
tools:context=".CharactersListFragment">
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:id="#+id/recycler_view"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent"
/>
</androidx.constraintlayout.widget.ConstraintLayout>
Layout for RecyclerView row: fragment_character_recyclerview_list.xml
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView 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"
android:id="#+id/character_card_view"
android:layout_width="match_parent"
android:layout_height="300dp"
android:elevation="15dp"
app:cardBackgroundColor="#color/violet_forcard"
app:cardCornerRadius="3dp">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent">
<ImageView
android:id="#+id/char_thumnail_img"
android:layout_width="143dp"
android:layout_height="150dp"
android:layout_marginStart="24dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.106"
tools:srcCompat="#tools:sample/avatars" />
<TextView
android:id="#+id/char_id_txt"
android:layout_width="190dp"
android:layout_height="53dp"
android:layout_marginTop="16dp"
android:fontFamily="#font/roboto"
android:text="Character ID: "
android:textAlignment="viewStart"
android:textColor="#color/white"
android:textSize="18sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/char_thumnail_img"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/char_name_txt"
android:layout_width="190dp"
android:layout_height="53dp"
android:layout_marginTop="24dp"
android:fontFamily="#font/roboto"
android:text="Name: "
android:textAlignment="viewStart"
android:textColor="#color/white"
android:textSize="18sp"
android:textStyle="bold"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/char_thumnail_img"
app:layout_constraintTop_toBottomOf="#+id/char_id_txt" />
<TextView
android:id="#+id/char_descp_txt"
android:layout_width="359dp"
android:layout_height="wrap_content"
android:fontFamily="#font/roboto"
android:textAlignment="viewStart"
android:textColor="#color/white"
android:textSize="14sp"
android:textStyle="bold"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintHorizontal_bias="0.461"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.918" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.cardview.widget.CardView>
Kotlin class for fragment: CharactersListFragment.kt
package com.example.marvelapp
import android.os.Bundle
import android.util.Log
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import retrofit2.Call
import retrofit2.Callback
import retrofit2.Response
class CharactersListFragment : Fragment() {
private lateinit var charsAdapter: CharacterListAdapter
private lateinit var apiService: APIService
private var characters: MutableList<Character> = ArrayList()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
// Inflate the layout for this fragment
Log.i("INSIDE_FRAGMENT_ONCREATEVIEW", "Fragment creation initiated")
val v = inflater.inflate(R.layout.fragment_characters_list, container, false)
apiService = RestClient.client.create(APIService::class.java)
getCharacterList()
val recycler_view = v.findViewById(R.id.recycler_view) as RecyclerView
recycler_view.layoutManager = LinearLayoutManager(activity)
charsAdapter = CharacterListAdapter()
recycler_view.adapter = charsAdapter
return v
}
private fun getCharacterList(){
val call = apiService!!.get_characters()
call.enqueue(object: Callback<List<Character>> {
override fun onResponse(
call: Call<List<Character>>,
response: Response<List<Character>>
) {
val chars = response.body()
Log.i("get_character_succeeded_FOR_CALL", chars.toString())
if (chars != null){
characters.addAll(chars!!)
Log.i("character_ADD_CHECK_INSIDE_FRAGMENT", characters[0].toString())
charsAdapter.submitDataforcharList(characters)
}
}
override fun onFailure(call: Call<List<Character>>, t: Throwable) {
Log.e("get_character_failed", t.localizedMessage)
}
})
}
}
Kotlin class for adapter: CharacterListAdapter.kt
package com.example.marvelapp
import android.text.Layout
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 kotlinx.android.synthetic.main.fragment_character_recyclerview_list.view.*
class CharacterListAdapter: RecyclerView.Adapter<RecyclerView.ViewHolder>() {
private var charItems: List<Character> = ArrayList()
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerView.ViewHolder {
Log.i("INSIDE_ONCREATE_VIEWHOLDER", "reached")
return CharacterListViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.fragment_character_recyclerview_list,
parent,
false))
}
override fun onBindViewHolder(holder: RecyclerView.ViewHolder, position: Int) {
when(holder){
is CharacterListViewHolder ->{
Log.i("VIEWHOLDER_FOUND", "proceeding to bind")
holder.bind(charItems.get(position))
}
}
}
override fun getItemCount(): Int {
Log.i("INSIDE_ADAPTER_GET_ITEM_COUNT", charItems.size.toString())
return charItems.size
}
fun submitDataforcharList (characterlist: List<Character>){
Log.i("INSIDE_ADAPTER_SUBMIT_DATA", characterlist[0].toString())
charItems = characterlist
}
class CharacterListViewHolder
constructor(view: View): RecyclerView.ViewHolder(view){
val char_id = view.findViewById<TextView>(R.id.char_id_txt)
val char_name = view.findViewById<TextView>(R.id.char_name_txt)
val char_descp = view.findViewById<TextView>(R.id.char_descp_txt)
fun bind(character: Character){
Log.i("INSIDE_VIEWHOLDER_BIND", character.toString())
val id = Integer.toString(character.charId)
val id_mess = "Character ID: $id"
char_id.setText(id_mess)
val char_name_mess = "Name: ${character.charName}"
char_name.setText(char_name_mess)
char_descp.setText(character.charDescp)
}
}
}
the Character model class:
package com.example.marvelapp
data class Character(
val charId: Int,
val charName: String,
val charDescp: String,
){
}
I am an android beginner and have been stuck at this for quite some time, any help will be highly appreciated.
Thanks in advance!

In the onCreateView of CharactersListFragment you are calling getCharacterList() and then you move on with your initialization of the recycler view. After the getCharacterList call completes, you might be getting some data and you are simply updating the data list in your adapter class but you are not informing your recyclerview to refresh the view to display the new data. So I think if you just call notifyDataSetChanged() on your adapter after setting the new data it should work.
The other way to solve the issue could be if you initialize your recyclerview after you've received the data from the getCharacterList() call and just show some loading icon in place of the recycler view while the data is being fetched.

getCharacterList() is called on UI thread (main thread) but communicating (requests and responses) between device and API server is happening in another thread, it means there is no guarantee that onResponse() will come earlier than recycler_view.adapter = charsAdapter and in reality, it mostly does not happens. Therefor, you must call charsAdapter.notifyDataSetChanged() after charsAdapter.submitDataforcharList(characters) to have the recyclerview represent data. Another more elegent way to do that is adding notifyDatasetChanged() inside submitDataforcharList():
fun submitDataforcharList (characterlist: List<Character>){
charItems = characterlist
notifyDatasetChanged()
}

RecyclerView doesn't scroll smoothly initially

I'm using Tmdb API and displaying it in a RecyclerView. The RecyclerView is not scrolling smoothly initially but then is working fine. I've tried to change Recyclerview height to 0dp or match_parent but it's still the same. I've tried also android:nestedScrollingEnabled="true". Please help me to fix this problem in the RecyclerView. Thank you in advance.
fragment_add.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"
xmlns:tools="http://schemas.android.com/tools">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".view.AddFragment">
<androidx.appcompat.widget.AppCompatAutoCompleteTextView
android:id="#+id/fragment_add_movieSeriesACT"
android:layout_width="match_parent"
android:layout_height="50dp"
android:layout_marginStart="24dp"
android:layout_marginTop="16dp"
android:layout_marginEnd="24dp"
android:background="#drawable/edit_text_background"
android:hint="#string/movie_or_series"
android:imeOptions="actionDone"
android:inputType="textEmailAddress"
android:paddingStart="8dp"
android:paddingEnd="8dp"
android:textColor="#color/colorPrimary"
android:textColorHint="#color/colorEight"
android:textCursorDrawable="#null"
android:textSize="15sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/fragment_add_mainRV"
android:layout_width="match_parent"
android:layout_height="0dp"
android:layout_marginTop="8dp"
android:scrollbars="vertical"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/fragment_add_movieSeriesACT" />
<ProgressBar
android:id="#+id/fragment_add_mainPB"
style="?android:attr/progressBarStyle"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:indeterminate="true"
android:indeterminateTint="#color/colorOne"
android:indeterminateTintMode="src_atop"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
AddFragment.kt
import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.Toast
import androidx.lifecycle.Observer
import androidx.lifecycle.ViewModelProviders
import androidx.recyclerview.widget.LinearLayoutManager
import com.martiandeveloper.muuvi.R
import com.martiandeveloper.muuvi.adapter.RecyclerViewMovieAdapter
import com.martiandeveloper.muuvi.viewmodel.AddViewModel
import kotlinx.android.synthetic.main.fragment_add.*
class AddFragment : Fragment() {
private lateinit var viewModel: AddViewModel
private val adapter = RecyclerViewMovieAdapter(arrayListOf())
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_add, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
initUI()
}
private fun initUI() {
viewModel = ViewModelProviders.of(this).get(AddViewModel::class.java)
setRecyclerView()
observe()
viewModel.refreshData()
}
private fun setRecyclerView() {
fragment_add_mainRV.layoutManager = LinearLayoutManager(context)
fragment_add_mainRV.adapter = adapter
}
private fun observe() {
viewModel.movieList.observe(viewLifecycleOwner, Observer { movieList ->
movieList?.let {
adapter.updateMovieList(it)
}
})
viewModel.isError.observe(viewLifecycleOwner, Observer { isError ->
isError?.let {
setProgress(1F, true, View.GONE)
if (it) {
setToast(resources.getString(R.string.something_went_wrong_please_try_again_later))
}
}
})
viewModel.isLoading.observe(viewLifecycleOwner, Observer { isLoading ->
isLoading?.let {
if (it) {
setProgress(.5F, false, View.VISIBLE)
} else {
setProgress(1F, true, View.GONE)
}
}
})
}
private fun setProgress(alpha: Float, enable: Boolean, visible: Int) {
fragment_add_movieSeriesACT.alpha = alpha
fragment_add_mainRV.alpha = alpha
fragment_add_movieSeriesACT.isEnabled = enable
fragment_add_mainPB.visibility = visible
}
private fun setToast(text: String) {
Toast.makeText(context, text, Toast.LENGTH_SHORT).show()
}
}
AddViewModel.kt
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import com.martiandeveloper.muuvi.model.MovieResult
import com.martiandeveloper.muuvi.model.Movie
import com.martiandeveloper.muuvi.service.MovieService
import io.reactivex.android.schedulers.AndroidSchedulers
import io.reactivex.disposables.CompositeDisposable
import io.reactivex.observers.DisposableSingleObserver
import io.reactivex.schedulers.Schedulers
class AddViewModel : ViewModel() {
private val movieService = MovieService()
private val disposable = CompositeDisposable()
val movieList = MutableLiveData<List<Movie>>()
val isError = MutableLiveData<Boolean>()
val isLoading = MutableLiveData<Boolean>()
fun refreshData() {
isLoading.value = true
disposable.add(
movieService.getData().subscribeOn(Schedulers.newThread())
.observeOn(AndroidSchedulers.mainThread())
.subscribeWith(object : DisposableSingleObserver<MovieResult>() {
override fun onSuccess(t: MovieResult) {
movieList.value = t.results
isError.value = false
isLoading.value = false
}
override fun onError(e: Throwable) {
isError.value = true
isLoading.value = false
}
})
)
}
}
RecyclerViewMovieAdapter.kt
import android.content.Context
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.bumptech.glide.Glide
import com.martiandeveloper.muuvi.R
import com.martiandeveloper.muuvi.model.Movie
import kotlinx.android.synthetic.main.recyclerview_movie_item.view.*
class RecyclerViewMovieAdapter(private val movieList: ArrayList<Movie>) :
RecyclerView.Adapter<RecyclerViewMovieAdapter.RecyclerViewMovieViewHolder>() {
lateinit var context: Context
class RecyclerViewMovieViewHolder(var view: View) : RecyclerView.ViewHolder(view)
override fun onCreateViewHolder(
parent: ViewGroup,
viewType: Int
): RecyclerViewMovieViewHolder {
context = parent.context
val view = LayoutInflater.from(context)
.inflate(R.layout.recyclerview_movie_item, parent, false)
return RecyclerViewMovieViewHolder(view)
}
override fun getItemCount(): Int {
return movieList.size
}
override fun onBindViewHolder(holder: RecyclerViewMovieViewHolder, position: Int) {
holder.view.recyclerview_movie_item_movieTitleMTV.text =
movieList[position].movieTitle
holder.view.recyclerview_movie_item_movieVoteAverageMTV.text =
movieList[position].movieVoteAverage.toString()
Glide.with(context)
.load("https://image.tmdb.org/t/p/w300${movieList[position].moviePosterPath}")
.into(holder.view.recyclerview_movie_item_moviePosterIV)
}
fun updateMovieList(newMovieList: List<Movie>) {
movieList.clear()
movieList.addAll(newMovieList)
notifyDataSetChanged()
}
}
recyclerview_movie_item.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="center_vertical"
android:paddingStart="16dp"
android:paddingTop="8dp"
android:paddingEnd="8dp"
android:paddingBottom="8dp">
<androidx.cardview.widget.CardView
android:layout_width="80dp"
android:layout_height="80dp"
app:cardBackgroundColor="#android:color/transparent"
app:cardCornerRadius="10dp"
app:cardElevation="0dp">
<ImageView
android:id="#+id/recyclerview_movie_item_moviePosterIV"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:contentDescription="#string/app_name"
android:scaleType="centerCrop"
app:srcCompat="#drawable/default_user_image" />
</androidx.cardview.widget.CardView>
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:orientation="vertical">
<com.google.android.material.textview.MaterialTextView
android:id="#+id/recyclerview_movie_item_movieTitleMTV"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#color/colorPrimary"
android:textSize="18sp"
android:textStyle="bold" />
<com.google.android.material.textview.MaterialTextView
android:id="#+id/recyclerview_movie_item_movieVoteAverageMTV"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textColor="#color/colorPrimaryDark" />
</LinearLayout>
</LinearLayout>

I believe this is due to size of the image , I had similar issue try to fit the image you obtain using glide into imageview, I have added centerCrop():
Glide.with(context).load("https://image.tmdb.org/t/p/w300${movieList[position].moviePosterPath}") .centerCrop().into(holder.view.recyclerview_movie_item_moviePosterIV);
If this does not work try to change imageview scaletype or centerCrop() to fitCenter()

I created a RecyclerView layout, but the look does not match what I expected

I created a RecyclerView layout, but the look does not match what I expected
I have checked layout_height on list_item.xml, but already wrap_content.
But why it looks does not fit.
And TextView with id tv_title_list not appear when executed
Display Screenshots : https://drive.google.com/open?id=1hywe6DrXth6iwO9jIgScAxhTq1Cq3mAL
For full code : https://github.com/riluq/AnimeApp
list_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"
xmlns:tools="http://schemas.android.com/tools">
<data>
<variable name="topAiring" type="com.riluq.animeapp.network.TopAiring"/>
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<com.google.android.material.card.MaterialCardView
android:id="#+id/mcv_list"
android:layout_width="65dp"
android:layout_height="90dp"
app:cardCornerRadius="5dp"
app:cardElevation="2dp"
app:layout_constraintTop_toTopOf="parent"
android:layout_marginBottom="16dp" app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintStart_toStartOf="parent" android:layout_marginStart="8dp"
android:layout_marginTop="16dp">
<ImageView
android:id="#+id/img_list"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:scaleType="centerCrop"
tools:srcCompat="#android:color/holo_blue_light"
app:imageUrl="#{topAiring.imageUrlTopAiring}"/>
</com.google.android.material.card.MaterialCardView>
<TextView
android:id="#+id/tv_title_list"
tools:text="JoJo no Kimyou na Bouken Part 5: Ougon no Kaze"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:textAppearance="#style/TextAppearance.MaterialComponents.Subtitle2"
app:layout_constraintStart_toEndOf="#+id/mcv_list"
android:layout_marginStart="8dp" app:layout_constraintTop_toTopOf="#+id/mcv_list"
app:layout_constraintBottom_toBottomOf="#+id/mcv_list"
android:layout_marginEnd="8dp" app:layout_constraintEnd_toStartOf="#+id/tv_rank_list"
app:textTopAiringTitle="#{topAiring.titleTopAiring}"/>
<TextView
android:id="#+id/tv_rank_list"
tools:text="#1"
android:textColor="?attr/colorSecondary"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:textAppearance="#style/TextAppearance.MaterialComponents.Headline5"
app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"
app:layout_constraintTop_toTopOf="#+id/mcv_list"
app:textTopAiringRank="#{topAiring.rankTopAiring}"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
fragment_top_airing.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"
xmlns:tools="http://schemas.android.com/tools">
<data>
<variable
name="viewModel"
type="com.riluq.animeapp.topairing.TopAiringViewModel"/>
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context=".topairing.TopAiringFragment">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rv_top_airing"
android:layout_width="0dp"
android:layout_height="0dp"
android:clipToPadding="false"
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:listData="#{viewModel.topAiring}"
tools:itemCount="16"
tools:listitem="#layout/list_item"/>
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
TopAiringAdapter.kt
package com.riluq.animeapp.topairing
import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.recyclerview.widget.DiffUtil
import androidx.recyclerview.widget.ListAdapter
import androidx.recyclerview.widget.RecyclerView
import com.riluq.animeapp.databinding.ListItemBinding
import com.riluq.animeapp.network.TopAiring
class TopAiringAdapter(): ListAdapter<TopAiring, TopAiringAdapter.TopAiringViewHolder>(DiffCallback) {
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): TopAiringViewHolder {
return TopAiringViewHolder(ListItemBinding.inflate(LayoutInflater.from(parent.context)))
}
override fun onBindViewHolder(holder: TopAiringViewHolder, position: Int) {
val topAiring = getItem(position)
holder.bind(topAiring)
}
class TopAiringViewHolder(private val binding: ListItemBinding) :
RecyclerView.ViewHolder(binding.root){
fun bind(topAiring: TopAiring) {
binding.topAiring = topAiring
binding.executePendingBindings()
}
}
companion object DiffCallback: DiffUtil.ItemCallback<TopAiring>() {
override fun areItemsTheSame(oldItem: TopAiring, newItem: TopAiring): Boolean {
return oldItem == newItem
}
override fun areContentsTheSame(oldItem: TopAiring, newItem: TopAiring): Boolean {
return oldItem.idTopAiring == newItem.idTopAiring
}
}
}
TopAiringFragment.kt
package com.riluq.animeapp.topairing
import android.os.Bundle
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.fragment.app.Fragment
import androidx.lifecycle.ViewModelProviders
import com.riluq.animeapp.databinding.FragmentTopAiringBinding
class TopAiringFragment : Fragment() {
private val viewModel: TopAiringViewModel by lazy {
ViewModelProviders.of(this).get(TopAiringViewModel::class.java)
}
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
val binding = FragmentTopAiringBinding.inflate(inflater)
binding.lifecycleOwner = this
// Inflate the layout for this fragment
binding.viewModel = viewModel
binding.rvTopAiring.adapter = TopAiringAdapter()
return binding.root
}
}
TopAiringViewModel.kt
package com.riluq.animeapp.topairing
import android.util.Log
import androidx.lifecycle.LiveData
import androidx.lifecycle.MutableLiveData
import androidx.lifecycle.ViewModel
import com.riluq.animeapp.network.JikanMoeApi
import com.riluq.animeapp.network.TopAiring
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.Job
import kotlinx.coroutines.launch
class TopAiringViewModel: ViewModel() {
private var viewModelJob = Job()
private val coroutineScope = CoroutineScope(viewModelJob + Dispatchers.Main)
private val _topAiring = MutableLiveData<List<TopAiring>>()
val topAiring: LiveData<List<TopAiring>>
get() = _topAiring
init {
getTopAiring()
}
private fun getTopAiring() {
coroutineScope.launch {
val getTopAiringDeffered = JikanMoeApi.retrofitService.getTopAiringAsync()
try {
val listResult = getTopAiringDeffered.await().top
if (listResult.size > 0) {
_topAiring.value = listResult
}
Log.i("TopAiringViewModel", "topAiring = ${topAiring.value?.get(0)?.titleTopAiring}")
} catch (t: Throwable) {
_topAiring.value = ArrayList()
Log.i("TopAiringViewModel", t.message.toString())
}
}
}
override fun onCleared() {
super.onCleared()
viewModelJob.cancel()
}
}
What I expected is the look like this picture : https://drive.google.com/open?id=1d1sWL0CX7gPJFvvhY13POWDAf15Hk2Pw

Add this property in recyclerview for left, right, top and bottom:
app:layout_constraintLeft_toLeftOf="parent"
app:layout_constraintRight_toRightOf="parent"
...like wise for top and bottom