How to populating RecyclerView in Kotlin

Welcome Coders ,

Here in this tutorial ,we are going to learn about populating RecyclerView in Kotlin

• Language – Kotlin
 
• Android studio – V 3.0.1

What we are going to Learn ? 

• RecyclerView Adapter in Kotlin
 
• Model Class in Kotlin
 
• for loop etc
 
• View Binding

Lets get started ,

Create a new application and choose basic activity as the template ,
Add recyclerview to your layout

– Drag and drop the recyclerview from the palette into the layout or create manually

Sample XML : content_main.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:layout_height="match_parent"
	app:layout_behavior="@string/appbar_scrolling_view_behavior"
	tools:context="in.yapp.recyclerviewexample.MainActivity"
	tools:showIn="@layout/activity_main">
	<android.support.v7.widget.RecyclerView
	android:id="@+id/recyclerView"
	android:layout_width="0dp"
	android:layout_height="0dp"
	android:layout_marginBottom="8dp"
	android:layout_marginEnd="8dp"
	android:layout_marginStart="8dp"
	android:layout_marginTop="8dp"
	app:layout_constraintBottom_toBottomOf="parent"
	app:layout_constraintEnd_toEndOf="parent"
	app:layout_constraintStart_toStartOf="parent"
	app:layout_constraintTop_toTopOf="parent" />
	</android.support.constraint.ConstraintLayout>

view rawcontent_main.xml hosted with ❤ by GitHub

Let’s Create a sample adapter for recyclerview with two textview

adapter.xml

	<?xml version="1.0" encoding="utf-8"?>
	<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
	android:layout_width="match_parent"
	android:layout_height="wrap_content"
	android:elevation="2dp"
	android:layout_margin="5dp">
	<TextView
	android:id="@+id/name"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_margin="5dp"
	android:textSize="18sp"
	android:textStyle="bold" />
	<TextView
	android:id="@+id/location"
	android:layout_width="wrap_content"
	android:layout_height="wrap_content"
	android:layout_below="@+id/name"
	android:layout_margin="5dp"/>
	</RelativeLayout>

view rawadapter.xml hosted with ❤ by GitHub

Model Class

Create a new Kotlin file from File -> New -> – Kotlin File/ Class

Name it as Model write the following code

Model.kt 

	package `in`.yapp.recyclerviewexample
	/**
	* Created by elstin on 12/30/2017.
	*/
	data class User(
	var name:String,
	var location:String
	)

view rawModel.Kt hosted with ❤ by GitHub

RecyclerView Adapter

Now we need a class to inflate the adapter layout we just created above ,

– Create a new Kotlin class and name it as Adapter.kt

Adapter.kt 

	package `in`.yapp.recyclerviewexample
	import android.content.Context
	import android.support.v7.widget.RecyclerView
	import android.view.LayoutInflater
	import android.view.View
	import android.view.ViewGroup
	import kotlinx.android.synthetic.main.adapter.view.*
	/**
	* Created by elstin on 12/30/2017.
	*/
	class Adapter constructor(private val list: List<User>, private val context: Context) : RecyclerView.Adapter<Adapter.setUpData>() {
	override fun onBindViewHolder(holder: setUpData, position: Int) {
	holder.dataBind(list[position], context)
	}
	override fun getItemCount(): Int {
	return list.size
	}
	override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): setUpData {
	val view = LayoutInflater.from(parent.context).inflate(R.layout.adapter, parent, false)
	return setUpData(view)
	}
	class setUpData(itemView: View?) : RecyclerView.ViewHolder(itemView) {
	fun dataBind(data: User, context: Context) {
	// No more find ViewByID
	itemView.name.text = data.name
	itemView.location.text = data.location
	}
	}
	}

view rawAdapter.kt hosted with ❤ by GitHub

Now comes the main part ;)

Lets Finalize the codes 

– Open the MainActivity.kt and make the following changes

MainActivity.kt 

	package `in`.yapp.recyclerviewexample
	import android.os.Bundle
	import android.support.v7.app.AppCompatActivity
	import android.support.v7.widget.LinearLayoutManager
	import kotlinx.android.synthetic.main.activity_main.*
	import kotlinx.android.synthetic.main.content_main.*
	class MainActivity : AppCompatActivity() {
	lateinit var userList : ArrayList<User>
	override fun onCreate(savedInstanceState: Bundle?) {
	super.onCreate(savedInstanceState)
	setContentView(R.layout.activity_main)
	setSupportActionBar(toolbar)
	userList = ArrayList()
	recyclerView.layoutManager = LinearLayoutManager(this)
	recyclerView.adapter = Adapter(userList,this)
	addDummyData()
	}
	private fun addDummyData() {
	val user0 = User("Leo Elstin", "Kaniyakumari,TN")
	userList.add(user0)
	val user1 = User("Bat Man", "Gotham")
	userList.add(user1)
	val user2 = User("Iorn Man", "New York")
	userList.add(user2)
	val user3 = User("Thor", "Parallel universe")
	userList.add(user3)
	val user4 = User("Loki", "Alien Planet")
	userList.add(user4)
	recyclerView.adapter.notifyDataSetChanged()
	}
	}

view rawMainActivity.kt hosted with ❤ by GitHub

Hit the run button and tadaa.. :p 

– Hope you learned something new :)