Recycler View not displaying inside a Fragment - kotlin

Question

I'm using Recycler view to show items in my Fragment named Recent History. I want to display user data from firebase to my recent history Fragment. But the recycler view is not showing on the fragment. Please Help me out in this. What did I do wrong here? or what's the solution so that my fragment shows the recycler view.
Recent History Fragment Code:
`
class recent_history : Fragment(R.layout.fragment_recent_history) {
private var binding: FragmentRecentHistoryBinding? = null
private lateinit var auth: FirebaseAuth
var database: FirebaseDatabase? = null
var databaseReference: DatabaseReference? = null
private lateinit var userArrayList: ArrayList<User>
private lateinit var myAdapter: AdapterClass
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
binding = FragmentRecentHistoryBinding.inflate(inflater, container, false)
return binding!!.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
auth = FirebaseAuth.getInstance()
database = FirebaseDatabase.getInstance()
databaseReference = database?.reference!!.child("Users").child("result")
userArrayList= arrayListOf()
myAdapter=AdapterClass(userArrayList)
binding?.recyclerview.apply {
binding?.recyclerview?.adapter = myAdapter
var linearLayoutManager = LinearLayoutManager(activity)
binding?.recyclerview?.layoutManager = linearLayoutManager
binding?.recyclerview?.setHasFixedSize(true)
}
getData()
}
override fun onDestroy() {
super.onDestroy()
binding = null
}
private fun getData() {
val user = auth.currentUser
databaseReference?.child(user?.uid!!)
databaseReference!!.addValueEventListener(object : ValueEventListener {
override fun onDataChange(snapshot: DataSnapshot) {
if (snapshot.exists()) {
for (data in snapshot.children) {
var model = data.getValue(User::class.java)
userArrayList.add(model!!)
}
}
}
override fun onCancelled(error: DatabaseError) {
Log.e("cancel", error.toString())
}
})
}
}
`
Fragment Recent History 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"
android:background="#color/white"
tools:context=".recent_history">
<TextView
android:id="#+id/profiletitle"
android:layout_width="389dp"
android:layout_height="46dp"
android:layout_marginStart="4dp"
android:layout_marginTop="28dp"
android:fontFamily="monospace"
android:text="Recent Search History"
android:textAlignment="center"
android:textColor="#color/Twit"
android:textSize="25sp"
android:textStyle="bold"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
</TextView>
<androidx.recyclerview.widget.RecyclerView
android:id="#+id/recyclerview"
android:layout_width="220dp"
android:layout_height="664dp"
android:layout_marginBottom="100dp"
android:orientation="vertical"
android:visibility="visible"
app:layout_constraintBottom_toBottomOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/profiletitle"
tools:listitem="#layout/adapterview">
</androidx.recyclerview.widget.RecyclerView>
</androidx.constraintlayout.widget.ConstraintLayout>
I'm sending data to firebase from another Fragment named keyword Fragment.
Code of keyword fragment:
class keywordfrag : Fragment() {
private var binding: FragmentKeywordfragBinding? = null
private lateinit var auth: FirebaseAuth
var database: FirebaseDatabase? = null
var databaseReference: DatabaseReference? = null
override fun onCreateView(
inflater: LayoutInflater,
container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
binding = FragmentKeywordfragBinding.inflate(inflater, container, false)
return binding!!.root
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
auth = FirebaseAuth.getInstance()
database = FirebaseDatabase.getInstance()
val user = auth.currentUser
databaseReference?.child(user?.uid!!)
databaseReference = database?.getReference("Users")?.child("result")
binding?.analyzebtn?.setOnClickListener {
sendData()
}
}
override fun onDestroy() {
super.onDestroy()
binding = null
}
private fun sendData() {
val keywordtext = binding?.userenteredkeyword?.text.toString().trim()
val timestamp = Timestamp(System.currentTimeMillis())
val timendate = timestamp.toString().trim()
// val username=auth.currentUser?.uid.toString().trim()
// val email=auth.currentUser?.email.toString().trim()
if (TextUtils.isEmpty(keywordtext)) {
binding?.userenteredkeyword?.error = "keyword can not be Empty"
} else {
val model = User(keywordtext, timendate)
val user = auth.currentUser
databaseReference?.child(user?.uid!!)?.setValue(model)
binding?.userenteredkeyword?.setText("")
val currentUser = auth.currentUser
val currentUserdb = databaseReference?.child((currentUser?.uid!!))
currentUserdb?.child("keywordtext")?.setValue(keywordtext)
currentUserdb?.child("timendate")?.setValue(timendate)
}
}
}
Adapter Class:
package com.example.emotela_finalyearproject
import android.view.LayoutInflater
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import com.example.emotela_finalyearproject.databinding.AdapterviewBinding
import kotlin.collections.ArrayList
class AdapterClass(var list:ArrayList<User>) :RecyclerView.Adapter<AdapterClass.ViewHolder>() {
class ViewHolder(val binding: AdapterviewBinding) : RecyclerView.ViewHolder(binding.root) {
var keyword = binding.keywordtv
var timenddate=binding.timendatetv
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder {
val binding = AdapterviewBinding.inflate(LayoutInflater.from(parent.context), parent, false)
return ViewHolder(binding)
}
override fun getItemCount(): Int {
return list.size
}
override fun onBindViewHolder(holder: ViewHolder, position: Int) {
with(holder) {
with(list[position]) {
keyword.text = this.keywordtext
timenddate.text= this.timendate
}
}
}
}
Adapter view Layout
<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
xmlns:app="http://schemas.android.com/apk/res-auto"
app:cardElevation="8dp"
app:cardCornerRadius="8dp"
android:layout_margin="16dp">
<LinearLayout
android:layout_width="200dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginVertical="6dp"
android:orientation="horizontal">
<LinearLayout
android:layout_width="336dp"
android:layout_height="match_parent"
android:layout_gravity="center_vertical"
android:orientation="vertical">
<TextView
android:id="#+id/keywordtitle"
android:layout_width="141dp"
android:layout_height="35dp"
android:fontFamily="monospace"
android:text="searched word: "
android:textSize="10sp"
android:textStyle="bold">
</TextView>
<TextView
android:id="#+id/keywordtv"
android:layout_width="143dp"
android:layout_height="36dp"
android:fontFamily="monospace"
android:textSize="10sp">
</TextView>
<TextView
android:id="#+id/timeanddatetitle"
android:layout_width="160dp"
android:layout_height="36dp"
android:fontFamily="monospace"
android:text="Time and Date: "
android:textSize="10sp"
android:textStyle="bold">
</TextView>
<TextView
android:id="#+id/timendatetv"
android:layout_width="171dp"
android:layout_height="48dp"
android:fontFamily="monospace"
android:textSize="10sp">
</TextView>
<LinearLayout
android:layout_width="200dp"
android:layout_height="wrap_content"
android:layout_marginStart="16dp"
android:layout_marginVertical="6dp"
android:orientation="horizontal">
<LinearLayout
android:layout_width="336dp"
android:layout_height="match_parent"
android:layout_gravity="center_vertical"
android:orientation="vertical">
</LinearLayout>
</LinearLayout>
</LinearLayout>
</LinearLayout>
</androidx.cardview.widget.CardView>
Result in Emulator:

Answer 1

You need to calll
imageAdapter.notifyDataSetChanged()
after you fetch the data from firebase.