I'm having trouble creating a Kotlin database adapter

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I'm trying to build a room database app with Kotlin. Database part is ok. I need to create adapter to show database data in Recyclerview. But I can't use the holder command. I think it might be related to "Kotlinx.Synthetic has been deprecated". I want to introduce textviews id's to adapter. When i try "holder.itemView.id_txt.text = currentItem.id.toString()" it does not recognize "id_txt.text". Can you help with introduce the custom row's textview ids to adapter. Thank you.

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User.kt

import androidx.room.Entity
import androidx.room.PrimaryKey

@Entity(tableName = "user_table")
data class User(
    @PrimaryKey(autoGenerate = true)
    val id: Int,
    val firstName: String,
    val lastName: String,
    val age: String
)

UserDao.kt

import androidx.lifecycle.LiveData
import androidx.room.Dao
import androidx.room.Insert
import androidx.room.OnConflictStrategy
import androidx.room.Query

@Dao
interface UserDao {

    @Insert(onConflict = OnConflictStrategy.IGNORE)
    suspend fun addUser(user: User)

    @Query("SELECT * FROM user_table ORDER BY id ASC")
    fun readAllData(): LiveData<List<User>>

}

UserDatabase.kt

import android.content.Context
import androidx.room.Database
import androidx.room.Room
import androidx.room.RoomDatabase

@Database(entities = [User::class], version = 1, exportSchema = false)
abstract class UserDatabase : RoomDatabase() {

    abstract fun userDao(): UserDao

    companion object {
        @Volatile
        private var INSTANCE: UserDatabase? = null

        fun getDatabase(context: Context): UserDatabase{
            val tempInstance = INSTANCE
            if(tempInstance != null){
                return tempInstance
            }
            synchronized(this){
                val instance = Room.databaseBuilder(
                    context.applicationContext,
                    UserDatabase::class.java,
                    "user_database"
                ).build()
                INSTANCE = instance
                return instance
            }
        }
    }

}

UserRepository.kt

import androidx.lifecycle.LiveData

class UserRepository(private val userDao: UserDao) {

    val readAllData: LiveData<List<User>> = userDao.readAllData()

    suspend fun addUser(user: User){
        userDao.addUser(user)
    }

}

UserViewModel.kt

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 UserViewModel(application: Application): AndroidViewModel(application) {

    private val readAllData: LiveData<List<User>>
    private val repository: UserRepository

    init {
        val userDao = UserDatabase.getDatabase(application).userDao()
        repository = UserRepository(userDao)
        readAllData = repository.readAllData
    }

    fun addUser(user: User){
        viewModelScope.launch(Dispatchers.IO) {
            repository.addUser(user)
        }
    }

}

AddFragment.kt

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.lifecycle.ViewModelProvider
import androidx.navigation.fragment.findNavController
import com.example.basehw.R
import com.example.basehw.data.UserViewModel
import com.example.basehw.databinding.FragmentAddBinding

import android.text.TextUtils
import android.widget.Toast
import com.example.basehw.data.User




class AddFragment : Fragment() {

    private lateinit var mUserViewModel: UserViewModel

    private var _binding: FragmentAddBinding? = null
    private val binding get() = _binding!!


    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        // Inflate the layout for this fragment
        _binding = FragmentAddBinding.inflate(inflater, container, false)


        mUserViewModel = ViewModelProvider(this).get(UserViewModel::class.java)

        binding.addBtn.setOnClickListener{

            insertDataToDatabase()
        }

        return binding.root
    }

    private fun insertDataToDatabase() {

        val firstName = binding.addFirstNameEt.text.toString()
        val lastName = binding.addFirstNameEt.text.toString()
        val age = binding.addAgeEt.text.toString()

        if(inputCheck(firstName, lastName, age)){
            // Create User Object
            val user = User(
                0,
                firstName,
                lastName,
                age
            )
            // Add Data to Database
            mUserViewModel.addUser(user)
            Toast.makeText(requireContext(), "Successfully added!", Toast.LENGTH_LONG).show()
            // Navigate Back
            findNavController().navigate(R.id.action_addFragment_to_listFragment)
        }else{
            Toast.makeText(requireContext(), "Please fill out all fields.", Toast.LENGTH_LONG).show()
        }
    }


    override fun onDestroy() {
        super.onDestroy()
    }


    private fun inputCheck(firstName: String, lastName: String, age: String): Boolean{
        return !(TextUtils.isEmpty(firstName) && TextUtils.isEmpty(lastName) && age.isEmpty())
    }

}

ListFragment.kt

import android.os.Bundle
import androidx.fragment.app.Fragment
import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.navigation.fragment.findNavController
import com.example.basehw.R
import com.example.basehw.databinding.FragmentListBinding


class ListFragment : Fragment() {

    private var _binding: FragmentListBinding? = null
    private val binding get() = _binding!!

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View {
        // Inflate the layout for this fragment
        _binding = FragmentListBinding.inflate(inflater, container, false)

        binding.floatingActionButton.setOnClickListener{

            findNavController().navigate(R.id.action_listFragment_to_addFragment)
        }

        return binding.root
    }


    override fun onDestroyView() {
        super.onDestroyView()
    }

}

ListAdapter.kt

import android.view.LayoutInflater
import android.view.View
import android.view.ViewGroup
import androidx.recyclerview.widget.RecyclerView
import androidx.viewpager2.adapter.FragmentViewHolder
import com.example.basehw.R
import com.example.basehw.data.User
import com.example.basehw.databinding.ActivityMainBinding
import com.example.basehw.databinding.FragmentListBinding

class ListAdapter: RecyclerView.Adapter<ListAdapter.MyViewHolder>() {


    private var binding: ActivityMainBinding? = null


    private var userList = emptyList<User>()

    class MyViewHolder(itemView: View): RecyclerView.ViewHolder(itemView) {}

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        return MyViewHolder(LayoutInflater.from(parent.context).inflate(R.layout.custom_row, parent, false))
    }

    override fun getItemCount(): Int {
        return userList.size
    }

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        val currentItem = userList[position]

        holder.itemView.id_txt.text = currentItem.id.toString()
        holder.itemView.firstName_txt.text = currentItem.firstName
        holder.itemView.lastName_txt.text = currentItem.lastName
        holder.itemView.age_txt.text = currentItem.age.toString()


    }

    fun setData(user: List<User>){
        this.userList = user
        notifyDataSetChanged()
    }
}

custom_row.xml

<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"
    android:id="@+id/custom_row"
    android:padding="24sp">

    <TextView
        android:id="@+id/id_txt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/_1"
        android:textSize="40sp"
        android:textStyle="bold"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/firstName_txt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="80dp"
        android:text="@string/john"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toEndOf="@+id/id_txt"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/lastName_txt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:text="@string/dao"
        android:textSize="24sp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toEndOf="@+id/firstName_txt"
        app:layout_constraintTop_toTopOf="parent" />

    <TextView
        android:id="@+id/age_txt"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginStart="8dp"
        android:textSize="24sp"
        android:text="@string/_25"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toEndOf="@+id/lastName_txt"
        app:layout_constraintTop_toTopOf="parent" />
</androidx.constraintlayout.widget.ConstraintLayout>

fragment_list.xml

<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=".fragments.list.ListFragment">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="409dp"
        android:layout_height="729dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.5"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <com.google.android.material.floatingactionbutton.FloatingActionButton
        android:id="@+id/floatingActionButton"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginEnd="24dp"
        android:layout_marginBottom="24dp"
        android:clickable="true"
        android:focusable="true"
        android:tint="@color/white"
        android:src="@drawable/ic_add"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        tools:ignore="SpeakableTextPresentCheck" />
</androidx.constraintlayout.widget.ConstraintLayout>
kotlin adapter database
1 Answers

As Kotlinx.Synthetics has been deprecated, you should use view binding which you are already using in your fragment and activity, you should also use it in your RecyclerView adapter.

Make a few changes in your recycler view adapter to work with view bindings.

class ListAdapter: RecyclerView.Adapter<ListAdapter.MyViewHolder>() {


    private var userList = emptyList<User>()

    class MyViewHolder(private val customRowBinding: CustomRowBinding): RecyclerView.ViewHolder(customRowBinding.root) {
        fun bind(user: User) {
                customRowBinding.idTxt.text = user.id.toString()
                customRowBinding.firstNameTxt.text = user.firstName
                customRowBinding.lastNameTxt.text = user.lastName
                customRowBinding.ageTxt.text = user.age.toString()
        }
    }

    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyViewHolder {
        return MyViewHolder(CustomRowBinding.inflate(LayoutInflater.from(parent.context), parent, false))
    }

    override fun getItemCount(): Int {
        return userList.size
    }

    override fun onBindViewHolder(holder: MyViewHolder, position: Int) {
        val currentItem = userList[position]
        holder.bind(currentItem)
    }

    fun setData(user: List<User>){
        this.userList = user
        notifyDataSetChanged()
    }
}

Instead of binding data inside onBindViewHolder, create a bind() method inside the view holder and bind there.

user_119831240
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