ROOM + Coroutine Flow - 7 (Room + Flow + ListAdapter CRUD)

 

buildscript {

    ext {
        room_version = '2.5.0'
    }

}

id 'kotlin-kapt'

// ROOM
implementation "androidx.room:room-runtime:$room_version"
kapt "androidx.room:room-compiler:$room_version"

// optional - Kotlin Extensions and Coroutines support for Room
implementation "androidx.room:room-ktx:$room_version"

// coroutine
implementation "androidx.lifecycle:lifecycle-runtime-ktx:2.5.1"

 

 

 

	class MainActivity : AppCompatActivity() {
	private lateinit var binding : ActivityMainBinding
	override fun onCreate(savedInstanceState: Bundle?) {
	super.onCreate(savedInstanceState)
	binding = ActivityMainBinding.inflate(layoutInflater)
	setContentView(binding.root)
	val db = MyDatabase.getDatabase(this)
	val recyclerView = binding.userRV
	val myListAdapter = MyListAdapter()
	recyclerView.adapter = myListAdapter
	recyclerView.layoutManager = LinearLayoutManager(this)
	binding.create.setOnClickListener {
	val name = binding.name.text.toString()
	val age = binding.age.text.toString()
	CoroutineScope(Dispatchers.IO).launch {
	val userEntity = UserEntity(0, name, age.toInt())
	db.userDao().insert(userEntity)
	}
	}
	binding.read.setOnClickListener {
	CoroutineScope(Dispatchers.IO).launch {
	db.userDao().getAllDataFlow().collect {
	withContext(Dispatchers.Main) {
	myListAdapter.submitList(it)
	}
	}
	}
	}
	binding.next.setOnClickListener {
	val intent = Intent(this, NextActivity::class.java)
	startActivity(intent)
	}
	}
	}

view raw MainActivity.kt hosted with ❤ by GitHub

	class MyListAdapter : ListAdapter<UserEntity, MyListAdapter.MyListAdapterViewHolder>(DiffCallback){
	companion object {
	private val DiffCallback = object : DiffUtil.ItemCallback<UserEntity>() {
	override fun areItemsTheSame(oldItem: UserEntity, newItem: UserEntity): Boolean {
	return oldItem.id == newItem.id
	}
	override fun areContentsTheSame(oldItem: UserEntity, newItem: UserEntity): Boolean {
	return oldItem == newItem
	}
	}
	}
	override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): MyListAdapterViewHolder {
	val viewHolder = MyListAdapterViewHolder(UserItemBinding.inflate(LayoutInflater.from(parent.context), parent, false))
	return viewHolder
	}
	override fun onBindViewHolder(holder: MyListAdapterViewHolder, position: Int) {
	holder.bind(getItem(position))
	}
	class MyListAdapterViewHolder(private var binding : UserItemBinding) : RecyclerView.ViewHolder(binding.root){
	fun bind(userEntity: UserEntity) {
	binding.id.text = userEntity.id.toString()
	binding.name.text = userEntity.name
	binding.age.text = userEntity.age.toString()
	}
	}
	}

view raw MyListAdapter.kt hosted with ❤ by GitHub

	class NextActivity : AppCompatActivity() {
	private lateinit var binding : ActivityNextBinding
	override fun onCreate(savedInstanceState: Bundle?) {
	super.onCreate(savedInstanceState)
	binding = ActivityNextBinding.inflate(layoutInflater)
	setContentView(binding.root)
	val db = MyDatabase.getDatabase(this)
	val recyclerView = binding.userRV
	val myListAdapter = MyListAdapter()
	recyclerView.adapter = myListAdapter
	recyclerView.layoutManager = LinearLayoutManager(this)
	binding.read.setOnClickListener {
	CoroutineScope(Dispatchers.IO).launch {
	db.userDao().getAllDataFlow().collect {
	withContext(Dispatchers.Main) {
	myListAdapter.submitList(it)
	}
	}
	}
	}
	binding.update.setOnClickListener {
	val id = binding.id.text.toString().toInt()
	CoroutineScope(Dispatchers.IO).launch {
	val result = db.userDao().getAllData()
	val userEntity = result[id]
	userEntity.name = "updated"
	db.userDao().update(userEntity)
	}
	}
	binding.remove.setOnClickListener {
	val id = binding.id.text.toString().toInt()
	CoroutineScope(Dispatchers.IO).launch {
	val result = db.userDao().getAllData()
	val userEntity = result[id]
	db.userDao().delete(userEntity)
	}
	}
	}
	}

view raw NextActivity.kt hosted with ❤ by GitHub

	@Database(entities = [UserEntity::class], version = 2)
	abstract class MyDatabase : RoomDatabase() {
	abstract fun userDao() : UserDao
	companion object {
	@Volatile
	private var INSTANCE : MyDatabase? = null
	fun getDatabase(
	context : Context
	) : MyDatabase {
	return INSTANCE ?:synchronized(this){
	val instance = Room.databaseBuilder(
	context.applicationContext,
	MyDatabase::class.java,
	"user_database"
	)
	.fallbackToDestructiveMigration()
	.build()
	INSTANCE = instance
	instance
	}
	}
	}
	}

view raw MyDatabase.kt hosted with ❤ by GitHub

	@Entity(tableName = "user_table")
	data class UserEntity (
	@PrimaryKey(autoGenerate = true)
	@ColumnInfo(name = "id")
	var id : Int = 0,
	@ColumnInfo(name = "name")
	var name : String,
	@ColumnInfo(name = "age")
	val age : Int
	)

view raw UserEntity.kt hosted with ❤ by GitHub

	@Dao
	interface UserDao {
	@Insert(onConflict = OnConflictStrategy.IGNORE)
	fun insert(user : UserEntity)
	@Query("SELECT * FROM user_table")
	fun getAllData() : List<UserEntity>
	@Query("SELECT * FROM user_table")
	fun getAllDataFlow() : Flow<List<UserEntity>>
	@Update
	fun update(userEntity: UserEntity)
	@Delete
	fun delete(userEntity: UserEntity)
	}

view raw UserDao.kt hosted with ❤ by GitHub

	<?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"
	xmlns:tools="http://schemas.android.com/tools"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	tools:context=".MainActivity"
	android:orientation="vertical">
	<androidx.cardview.widget.CardView
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:padding="10dp"
	android:layout_margin="10dp">
	<EditText
	android:id="@+id/name"
	android:background="@android:color/transparent"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_margin="10dp"
	android:hint="name"/>
	</androidx.cardview.widget.CardView>
	<androidx.cardview.widget.CardView
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:padding="10dp"
	android:layout_margin="10dp">
	<EditText
	android:id="@+id/age"
	android:background="@android:color/transparent"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_margin="10dp"
	android:hint="age"/>
	</androidx.cardview.widget.CardView>
	<Button
	android:id="@+id/create"
	android:text="create"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_margin="5dp"/>
	<Button
	android:id="@+id/read"
	android:text="read"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_margin="5dp"/>
	<Button
	android:id="@+id/next"
	android:text="next"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_margin="5dp"/>
	<androidx.recyclerview.widget.RecyclerView
	android:id="@+id/userRV"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	/>
	</LinearLayout>

view raw activity_main.xml hosted with ❤ by GitHub

	<?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"
	xmlns:tools="http://schemas.android.com/tools"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	tools:context=".NextActivity"
	android:orientation="vertical">
	<androidx.cardview.widget.CardView
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:padding="10dp"
	android:layout_margin="10dp">
	<EditText
	android:id="@+id/id"
	android:background="@android:color/transparent"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_margin="10dp"
	android:hint="id"/>
	</androidx.cardview.widget.CardView>
	<Button
	android:id="@+id/read"
	android:text="read"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_margin="5dp"/>
	<Button
	android:id="@+id/update"
	android:text="update"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_margin="5dp"/>
	<Button
	android:id="@+id/remove"
	android:text="remove"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:layout_margin="5dp"/>
	<androidx.recyclerview.widget.RecyclerView
	android:id="@+id/userRV"
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	/>
	</LinearLayout>

view raw activity_next.xml hosted with ❤ by GitHub

	<?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="80dp">
	<androidx.cardview.widget.CardView
	android:layout_width="match_parent"
	android:layout_height="match_parent"
	>
	<TextView
	android:id="@+id/id"
	android:text="id"
	android:layout_margin="20dp"
	android:textSize="30dp"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"/>
	<TextView
	android:id="@+id/name"
	android:text="name"
	android:layout_marginLeft="70dp"
	android:layout_marginTop="20dp"
	android:textSize="30dp"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"/>
	<TextView
	android:id="@+id/age"
	android:text="age"
	android:textSize="30dp"
	android:layout_marginTop="20dp"
	android:layout_marginLeft="200dp"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"/>
	</androidx.cardview.widget.CardView>
	</androidx.constraintlayout.widget.ConstraintLayout>

view raw user_item.xml hosted with ❤ by GitHub