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.

Only one item showing in Recyclerview? Item layout height is also "wrap content"

Only one item in my database is showing up in the RecyclerView. As per other answers on other posts, people repeatedly said to change the layout height of the item to "wrap content". But it didnt work. The getItemsCount() method also returns 1, so i think there may be a problem with the adapter, but i cant figure out what it is. i used a prepoluted database file and stored it in my assets folder.
Here are my classes:
Adapter:
package com.example.futsalnepalapp.files.adapters
import android.util.Log
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.example.futsalnepalapp.R
import com.example.futsalnepalapp.files.util.Futsal
import kotlinx.android.synthetic.main.item_futsal_info.view.*
class FutsalAdapter(var futsals: List<Futsal>) : RecyclerView.Adapter<FutsalAdapter.FutsalViewHolder>() {
inner class FutsalViewHolder(itemView : View): RecyclerView.ViewHolder(itemView)
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): FutsalViewHolder {
val view = LayoutInflater.from(parent.context).inflate(
R.layout.item_futsal_info,
parent,
false
)
return FutsalViewHolder(view)
}
override fun onBindViewHolder(holder: FutsalViewHolder, position: Int) {
holder.itemView.apply {
tvFutsalName.text = futsals[position].name
tvAddress.text = futsals[position].address
tvTole.text = futsals[position].tole
tvCity.text = futsals[position].city
tvPhoneNumber.text = futsals[position].phoneNumber
tvHoursOpen.text = futsals[position].hoursOpen
}
}
override fun getItemCount(): Int {
val size = futsals.size
Log.d("LIST_SIZE" , "the list size is: $size")
return size
}
}
Home Fragment:
package com.example.futsalnepalapp.files.ui.fragments
import android.os.Bundle
import android.view.View
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.futsalnepalapp.R
import com.example.futsalnepalapp.files.adapters.FutsalAdapter
import com.example.futsalnepalapp.files.ui.FutsalActivity
import com.example.futsalnepalapp.files.ui.FutsalViewModel
import kotlinx.android.synthetic.main.fragment_home.*
class HomeFragment : Fragment(R.layout.fragment_home) {
lateinit var viewModel: FutsalViewModel
lateinit var futsalAdapter: FutsalAdapter
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = (activity as FutsalActivity).viewModel
futsalAdapter = FutsalAdapter(listOf())
rvFutsalInfos.apply {
adapter = futsalAdapter
layoutManager = LinearLayoutManager(activity)
}
viewModel.getAllFutsals().observe(viewLifecycleOwner, Observer {
futsalAdapter.futsals = it
})
}
}
ViewModel:
package com.example.futsalnepalapp.files.ui.fragments
import android.os.Bundle
import android.view.View
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.futsalnepalapp.R
import com.example.futsalnepalapp.files.adapters.FutsalAdapter
import com.example.futsalnepalapp.files.ui.FutsalActivity
import com.example.futsalnepalapp.files.ui.FutsalViewModel
import kotlinx.android.synthetic.main.fragment_home.*
class HomeFragment : Fragment(R.layout.fragment_home) {
lateinit var viewModel: FutsalViewModel
lateinit var futsalAdapter: FutsalAdapter
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = (activity as FutsalActivity).viewModel
futsalAdapter = FutsalAdapter(listOf())
rvFutsalInfos.apply {
adapter = futsalAdapter
layoutManager = LinearLayoutManager(activity)
}
viewModel.getAllFutsals().observe(viewLifecycleOwner, Observer {
futsalAdapter.futsals = it
})
}
}
MainActivity:
package com.example.futsalnepalapp.files.ui.fragments
import android.os.Bundle
import android.view.View
import androidx.fragment.app.Fragment
import androidx.lifecycle.Observer
import androidx.recyclerview.widget.LinearLayoutManager
import com.example.futsalnepalapp.R
import com.example.futsalnepalapp.files.adapters.FutsalAdapter
import com.example.futsalnepalapp.files.ui.FutsalActivity
import com.example.futsalnepalapp.files.ui.FutsalViewModel
import kotlinx.android.synthetic.main.fragment_home.*
class HomeFragment : Fragment(R.layout.fragment_home) {
lateinit var viewModel: FutsalViewModel
lateinit var futsalAdapter: FutsalAdapter
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
viewModel = (activity as FutsalActivity).viewModel
futsalAdapter = FutsalAdapter(listOf())
rvFutsalInfos.apply {
adapter = futsalAdapter
layoutManager = LinearLayoutManager(activity)
}
viewModel.getAllFutsals().observe(viewLifecycleOwner, Observer {
futsalAdapter.futsals = it
})
}
}
Database:
package com.example.futsalnepalapp.files.database
import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase
import androidx.room.TypeConverters
import com.example.futsalnepalapp.files.util.Futsal
#Database(
entities = [Futsal::class],
version = 1
)
#TypeConverters(Converters::class)
abstract class FutsalDatabase : RoomDatabase() {
abstract fun getFutsalDao(): FutsalDao
companion object {
#Volatile
private var instance: FutsalDatabase? = null
private val LOCK = Any()
operator fun invoke(context: Context) = instance ?: synchronized(LOCK) {
instance ?: createDatabase(context).also {instance = it}
}
private fun createDatabase(context: Context) =
Room.databaseBuilder(
context.applicationContext,
FutsalDatabase::class.java,
"futsal_db.db"
).createFromAsset("database/futsalinfo.db").build()
}
}
item.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"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:padding="16dp">
<TextView
android:id="#+id/tvFutsalName"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Name"
android:textSize="24dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<TextView
android:id="#+id/tvAddress"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="24dp"
android:text="Address,"
android:textSize="16dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/tvFutsalName" />
<TextView
android:id="#+id/tvTole"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="24dp"
android:text=" Tole,"
android:textSize="16dp"
app:layout_constraintStart_toEndOf="#+id/tvAddress"
app:layout_constraintTop_toBottomOf="#+id/tvFutsalName" />
<TextView
android:id="#+id/tvCity"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="24dp"
android:text=" City"
android:textSize="16dp"
app:layout_constraintStart_toEndOf="#+id/tvTole"
app:layout_constraintTop_toBottomOf="#+id/tvFutsalName" />
<TextView
android:id="#+id/tvPhoneNumber"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="24dp"
android:text="Phone Number"
android:textSize="16dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/tvAddress" />
<TextView
android:id="#+id/tvHoursOpen"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_marginTop="24dp"
android:text="Hours Open"
android:textSize="16dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="#+id/tvAddress" />
</androidx.constraintlayout.widget.ConstraintLayout>
home_fragment.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="match_parent">
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/rvFutsalInfos"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
I tried changing the height of the item.xml to wrap content but nothing changed.
Do I have to increment the position variable like a loop in the onViewBinder function in the Adapter class?
I think there is something wrong with the amount of viewholders that are being created.

Recyclerview No adapter attached; skipping layout (Kotlin)

i'd like to know what i'm doing wrong over here. I'm building a CRUD app in Kotlin, and i'm using the recyclerview to make the readData page. The problem is, when i'm on the readData page doesn't show me anything, just the text views, so i debugged and when i join in the page, show this message: "Recyclerview No adapter attached; skipping layout".
Here's my code:
(i'm brazilian, so, some words are in portuguese, but you'll get it.)
verDados.kt
package com.nicolas.csrd
import android.content.Intent
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.widget.Toast
import com.google.firebase.database.*
import kotlinx.android.synthetic.main.activity_ver_database.*
import kotlinx.coroutines.Dispatchers
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.launch
import kotlinx.coroutines.withContext
class verDados : AppCompatActivity() {
private lateinit var database: FirebaseDatabase
private lateinit var reference: DatabaseReference
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_ver_database)
database = FirebaseDatabase.getInstance()
reference = database.getReference("usuarios")
verDados()
btn_voltar.setOnClickListener() {
startActivity(Intent(this#verDados, Dashboard::class.java))
finish()
}
}
private fun verDados() {
reference.addValueEventListener(object: ValueEventListener{
override fun onCancelled(p0: DatabaseError) {
Log.e("cancelar", p0.toString())
}
override fun onDataChange(p0: DataSnapshot) {
//Colocando os usuarios numa lista
var list = ArrayList<DatabaseModelo>()
for (data in p0.children) {
val model = data.getValue(DatabaseModelo::class.java)
list.add(model as DatabaseModelo)
}
if (list.size > 0) {
val ususariosModelo = usuariosModelo(list)
recyclerview.adapter = ususariosModelo
}
}
})
}
}
DatabaseModel
package com.nicolas.csrd
class DatabaseModelo() {
lateinit var email: String
lateinit var senha: String
constructor(email: String, senha: String) : this() {
this.email = email
this.senha = senha
}
}
usuariosModelo.kt (recyclerview adapter)
package com.nicolas.csrd
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.appcompat.view.menu.ActionMenuItemView
import androidx.appcompat.view.menu.MenuView
import androidx.recyclerview.widget.RecyclerView
import kotlinx.android.synthetic.main.usuarios_modelo.view.*
class usuariosModelo(val list: ArrayList<DatabaseModelo>): RecyclerView.Adapter<usuariosModelo.ViewHolder>() {
class ViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {
val email = itemView.campo_email
val senha = itemView.campo_senha
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
return ViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.usuarios_modelo, parent, false))
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
holder.email.text = list[position].email
holder.senha.text = list[position].senha
}
override fun getItemCount(): Int {
return list.size
}
}
----- XML FILES -----
activity_ver_database.xml (read data page)
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 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"
android:background="#color/dark"
tools:context=".Login">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:gravity="center_horizontal" >
<ImageView
android:id="#+id/btn_voltar"
android:layout_width="50dp"
android:layout_height="30dp"
android:layout_gravity="start"
android:layout_marginStart="5dp"
android:layout_marginTop="23dp"
android:src="#drawable/back_arrow" />
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="DADOS"
android:textColor="#7ec1d1"
android:textSize="30sp"
android:textStyle="bold"
android:layout_marginTop="20dp"
android:letterSpacing="0.15"
android:fontFamily="#font/montserrat_medium"
/>
<TextView
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Todos os usuários cadastrados"
android:textColor="#7ec1d1"
android:textSize="20sp"
android:textStyle="bold"
android:layout_marginTop="0dp"
android:fontFamily="#font/montserrat_thin"
/>
<androidx.recyclerview.widget.RecyclerView
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:id="#+id/recyclerview"
android:layout_margin="10sp"/>
<TextView
android:id="#+id/btn_cadastrar"
android:layout_width="350dp"
android:layout_height="50dp"
android:layout_marginTop="30dp"
android:backgroundTint="#7ec1d1"
android:gravity="center_horizontal"
android:fontFamily="#font/montserrat_regular"
android:text="Deseja cadastrar alguém? Clique aqui."
android:textColor="#color/white2"
android:textSize="15sp" />
</LinearLayout>
</LinearLayout>

You are getting this error because you have no defined an adaptor for the RecyclerView that you are using. Somewhere inn your onCreate method, create the adaptor and set it to the RecyclerView. Something like:
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_ver_database)
recyclerView = findViewById(R.id.recyclerview)
recyclerView.apply {
adapter = usuariosModelo(listOfItems)
}
database = FirebaseDatabase.getInstance()
reference = database.getReference("usuarios")
verDados()
btn_voltar.setOnClickListener() {
startActivity(Intent(this#verDados, Dashboard::class.java))
finish()
}
}

i solve the problem just adding the tag below inside the recyclerview tag in the .xml file:
app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager"
I hope that help y'all!

Audio SeekBar issue in android studio

package com.example.va_embedding
import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.util.Log
import android.view.View
import android.widget.MediaController
import android.widget.ProgressBar
import android.widget.SeekBar
import android.widget.VideoView
import android.widget.SeekBar.OnSeekBarChangeListener
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val venom = findViewById<VideoView>(R.id.venomvideo)
venom.setVideoPath("android.resource://" + packageName + "/" + R.raw.venom)
val mediaC = MediaController(this)
mediaC.setAnchorView(venom)
venom.setMediaController(mediaC)
val vc = findViewById<SeekBar>(R.id.seekBar2)
vc.setOnSeekBarChangeListener(SeekBar.OnSeekBarChangeListener(){
#Override
onProgressChanged(SeekBar seekBar2, Int: i, boolean : b)
Log.i(:"Seekbar changed", i = Integer.toString())
})
venom.start()
}
}
XML Layout
<?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">
<VideoView
android:id="#+id/venomvideo"
android:layout_width="333dp"
android:layout_height="568dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintVertical_bias="0.0" />
<SeekBar
android:id="#+id/seekBar2"
android:layout_width="249dp"
android:layout_height="73dp"
android:layout_marginStart="70dp"
android:layout_marginEnd="70dp"
android:layout_marginBottom="50dp"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>
Objective: To get an Audio SeekBar in the app
Issue: I am getting an error saying Interface do not have constructors. I am also facing an issue when I am trying to add OnSeekBarChangeListener() method.
I am using Android Studio 3.6.1.
My SDK version is 28
Kindly help

SeekBar.OnSeekBarChangeListener is an interface not a class, you can not call the constructor SeekBar.OnSeekBarChangeListener().
So instead use the below code:
vc.setOnSeekBarChangeListener(object: SeekBar.OnSeekBarChangeListener{
#Override
override fun onProgressChanged(
seekBar: SeekBar?, progress: Int,
fromUser: Boolean
){
Log.i(:"Seekbar changed", i = Integer.toString())
}
})

How to make Android RecyclerView invisible by clicking button inside itself?

Here's the minimal test case what I've managed to make.
It combines with a RecyclerView and TextView, the activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<TextView
android:id="#+id/textViewBatteryInfo"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="Hi, I'm watching you!"/>
<android.support.v7.widget.RecyclerView
android:id="#+id/my_rv"
android:layout_width="match_parent"
android:layout_height="match_parent"/>
</LinearLayout>
With the MainActivity.kt:
package kot.bignerd.recyclerview101
import android.support.v7.app.AppCompatActivity
import android.os.Bundle
import android.support.v7.widget.LinearLayoutManager
import android.view.View
import kotlinx.android.synthetic.main.activity_main.*
class MainActivity : AppCompatActivity() {
override fun onCreate(savedInstanceState: Bundle?) {
super.onCreate(savedInstanceState)
setContentView(R.layout.activity_main)
val items = arrayListOf<String>()
for (i in 10..50) {
items.add("Here's the $i th")
}
my_rv.layoutManager = LinearLayoutManager(this)
my_rv.adapter = MyListAdapter(items, this)
//my_rv.visibility = View.GONE
}
}
With a very simple adapter(MyListAdapter):
package kot.bignerd.recyclerview101
import android.content.Context
import android.support.v7.widget.RecyclerView
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
class MyListAdapter(val datas: List<String>, val context: Context) : RecyclerView.Adapter<MyListAdapter.InnerHolder>() {
override fun onCreateViewHolder(p0: ViewGroup, p1: Int): MyListAdapter.InnerHolder {
var itemView: View = LayoutInflater.from(context).inflate(R.layout.item_rv, p0, false)
return InnerHolder(itemView)
}
override fun getItemCount(): Int = datas.size
class InnerHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
var itemText: TextView = itemView.findViewById(R.id.item_tv)
}
override fun onBindViewHolder(p0: MyListAdapter.InnerHolder, p1: Int) {
p0?.itemText?.text = datas[p1]
}
}
The R.layout.item_rv mentioned in the adapter is (item_rv.xml):
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.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:id="#+id/item_cl"
android:layout_height="wrap_content">
<TextView
android:id="#+id/item_tv"
android:layout_width="0dp"
android:layout_height="50dp"
android:text="TestRV"
android:textSize="18sp"
android:gravity="center"
app:layout_constraintRight_toRightOf="parent"
app:layout_constraintLeft_toLeftOf="parent" tools:layout_editor_absoluteY="16dp"
app:layout_constraintHorizontal_bias="0.0"/>
<Button
android:text="Close"
android:layout_width="86dp"
android:layout_height="wrap_content" tools:layout_editor_absoluteY="16dp"
android:id="#+id/button" app:layout_constraintEnd_toEndOf="parent" android:layout_marginEnd="8dp"/>
</android.support.constraint.ConstraintLayout>
I was wondering if maybe we could make the RecyclerView disappeared when I click any one of the button inside it? Just like the code my_rv.visibility = View.GONE in the MainActivity.kt:

Your adapter need to receive a Listener as an object in order to react to clicks.
Here's an example:
package kot.bignerd.recyclerview101
import android.content.Context
import android.support.v7.widget.RecyclerView
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
class MyListAdapter(val datas: List<String>, val context: Context, val clickListener: ClickListener) : RecyclerView.Adapter<MyListAdapter.InnerHolder>() {
public interface ClickListener {
fun onItemClicked()
}
override fun onCreateViewHolder(p0: ViewGroup, p1: Int): MyListAdapter.InnerHolder {
var itemView: View = LayoutInflater.from(context).inflate(R.layout.item_rv, p0, false)
return InnerHolder(itemView)
}
override fun getItemCount(): Int = datas.size
class InnerHolder(itemView: View) : RecyclerView.ViewHolder(itemView) {
var itemText: TextView = itemView.findViewById(R.id.item_tv)
var button: Button = itemView.findViewById(R.id. button)
fun bindView(text: String, clickListener: ClickListener) {
itemText.text = text
button.setOnClickListner {
clickListner.onItemClicked()
}
}
}
override fun onBindViewHolder(holder: MyListAdapter.InnerHolder, position: Int) {
holder.bindView(datas[position], clickListener)
}
}
Then change the signature of the activity as follow:
class MainActivity : AppCompatActivity(), ClickListener {
and implement the function as follow:
override fun onItemClicked() {
my_rv.visibility = View.GONE
}
Last, but not least, change how you initialise your adapter:
MyListAdapter(items, this, this)