Why my realtime databaase cannot be worked? - android-studio

Question

I have faced the problem that my firebase cannot be worked as well and it just shows me nothing ( white page ) in my application. I need to use firebase to show the material in the recycler view. However, as the new user for firebase, I set my recycler view in string form and after it, I also want to use as one is image one is text. But I think that I need to fix the first problem as well. Can somebody help me? Thank you for your help!!
My original code :
package com.example.assignment_mad
import android.content.ContentValues.TAG
import android.content.Intent
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 android.widget.TextView
import android.widget.Toast
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView
import androidx.viewpager2.widget.ViewPager2
import com.example.assignment_mad.databinding.ActivityMainBinding
import com.example.assignment_mad.databinding.FragmentNotificationBinding
import com.example.assignment_mad.databinding.FragmentSearchPageBinding
import com.google.android.material.imageview.ShapeableImageView
import com.google.android.material.tabs.TabLayout
import com.google.firebase.database.*
import com.google.firebase.database.ktx.database
import com.google.firebase.ktx.Firebase
import kotlinx.android.synthetic.*
import kotlinx.android.synthetic.main.activity_main.*
import kotlinx.android.synthetic.main.fragment_notification_.*
class Notification_Fragment : Fragment( ) {
val database=Firebase.database
val myRef=database.getReference("message")
private var _binding:FragmentNotificationBinding?=null
private val binding get()=_binding!!
private lateinit var dbref: DatabaseReference
private lateinit var newRecyclerView: RecyclerView
private lateinit var newArrayList: ArrayList<Company>
private lateinit var tempArrayList: ArrayList<Company>
lateinit var imageId:Array<Int>
lateinit var heading:Array<String>
lateinit var news:Array<String>
private var layoutManager: RecyclerView.LayoutManager? = null
private var adapter: RecyclerView.Adapter<NotificationAdapter.MyViewHolder>? = null
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
var views =inflater.inflate(R.layout.fragment_notification_, container, false)
newRecyclerView=views.findViewById(R.id.recyclerView)
// Inflate the layout for this fragment
return views
}
override fun onViewCreated(itemView: View, savedInstanceState: Bundle?) {
super.onViewCreated(itemView, savedInstanceState)
newArrayList= arrayListOf<Company>()
tempArrayList= arrayListOf<Company>()
getUserdata()
}
private fun getUserdata() {
dbref=FirebaseDatabase.getInstance().getReference("Notification")
dbref.addValueEventListener(object : ValueEventListener {
override fun onDataChange(snapshot: DataSnapshot) {
if (snapshot.exists()){
for (companySnapshot in snapshot.children){
val company=companySnapshot.getValue(Company::class.java)
newArrayList.add(company!!)
}
newRecyclerView.adapter=NotificationAdapter(newArrayList)
}
}
override fun onCancelled(error: DatabaseError) {
Log.w(TAG, "Failed to read value.", error.toException())
}
})
newRecyclerView.layoutManager=LinearLayoutManager(activity)
newRecyclerView.setHasFixedSize(true)
newRecyclerView.adapter=adapter
}
}
The adapter code :
package com.example.assignment_mad
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import android.widget.TextView
import androidx.recyclerview.widget.RecyclerView
import com.google.android.material.imageview.ShapeableImageView
import kotlinx.android.synthetic.main.dropdown_item.view.*
class NotificationAdapter(private val companysList:ArrayList<Company>):RecyclerView.Adapter<NotificationAdapter.MyViewHolder>() {
private var mListener:onItemClickListener?=null
interface onItemClickListener{
fun onItemClick(position: Int)
}
fun setOnItemClickListener(listener: onItemClickListener){
mListener=listener
}
override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
val itemView=LayoutInflater.from(parent.context).inflate(R.layout.list_item,parent,false)
return MyViewHolder(itemView,mListener)
}
override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
val currentItem=companysList[position]
holder.titleImage.text=currentItem.titleImage
// holder.titleImage.setImageResource(currentItem.titleImage)
holder.tvHeading.text=currentItem.heading
}
override fun getItemCount(): Int {
return companysList.size
}
//to insert the post detail
class MyViewHolder(itemView: View,listener: onItemClickListener?):RecyclerView.ViewHolder(itemView){
val titleImage:TextView=itemView.findViewById(R.id.title_image)
// val titleImage:ShapeableImageView=itemView.findViewById(R.id.title_image)
val tvHeading: TextView =itemView.findViewById(R.id.tvHeading)
init {
itemView.setOnClickListener{
listener?.onItemClick(adapterPosition)
}
}
}
}
Data :
package com.example.assignment_mad
data class Company(var titleImage:String?=null,var heading:String?=null)
//data class Company(var titleImage:Int,var heading:String)
The xml file ( as you see, actually i need image and text together ) :
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
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"
android:layout_margin="8dp">
<!-- <com.google.android.material.imageview.ShapeableImageView-->
<!-- android:layout_width="80dp"-->
<!-- android:layout_height="80dp"-->
<!-- android:id="#+id/title_image"-->
<!-- android:scaleType="centerCrop"-->
<!-- app:layout_constraintStart_toStartOf="parent"-->
<!-- app:layout_constraintTop_toTopOf="parent"-->
<!-- app:shapeAppearanceOverlay="#style/RoundCorner"-->
<!-- android:src="#drawable/company_logo_1"/> -->
<TextView
android:id="#+id/title_image"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:textColor="#color/black"
android:text="Self Brief"
android:textSize="16dp"
android:textStyle="bold"
android:layout_marginStart="16dp"
android:layout_marginEnd="32dp"
android:layout_marginTop="8dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<TextView
android:id="#+id/tvHeading"
android:layout_width="0dp"
android:layout_height="wrap_content"
android:textColor="#color/black"
android:text="Candidate Biden Called Saudi Arable a Pareft eaft."
android:textSize="16dp"
android:textStyle="bold"
android:layout_marginStart="16dp"
android:layout_marginEnd="32dp"
android:layout_marginTop="8dp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toEndOf="#+id/title_image"
app:layout_constraintTop_toTopOf="parent"/>
<View
android:layout_width="match_parent"
android:layout_height="1dp"
android:layout_margin="8dp"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="#+id/title_image"
android:background="#color/underline"/>
</androidx.constraintlayout.widget.ConstraintLayout>
These is the problem faced. Or some one else can directly teach me how to set image for realtime database?
My database pic :

Answer 1

Your RecyclerView is showing no item because you are never initializing the adapter variable, which you are setting to your RecyclerView's adapter. Initialize adapter variable inside onViewCreated()
override fun onViewCreated(itemView: View, savedInstanceState: Bundle?) {
super.onViewCreated(itemView, savedInstanceState)
newArrayList= arrayListOf<Company>()
tempArrayList= arrayListOf<Company>()
adapter = NotificationAdapter(newArrayList) //Initialize adapter
getUserdata()
}
Inside onDataChange(), after adding data to newArrayList, notify adapter by calling notifyDataSetChanged() on adapter. It would update the RecyclerView.
private fun getUserdata() {
dbref=FirebaseDatabase.getInstance().getReference("Notification")
dbref.addValueEventListener(object : ValueEventListener {
override fun onDataChange(snapshot: DataSnapshot) {
if (snapshot.exists()){
for (companySnapshot in snapshot.children){
val company=companySnapshot.getValue(Company::class.java)
newArrayList.add(company!!)
}
adapter.notifyDataSetChanged()
}
}
override fun onCancelled(error: DatabaseError) {
Log.w(TAG, "Failed to read value.", error.toException())
}
})
newRecyclerView.layoutManager=LinearLayoutManager(activity)
newRecyclerView.setHasFixedSize(true)
newRecyclerView.adapter = adapter
}