Android RecyclerView in Kotlin
Last Updated : 25 Feb, 2025
In this article, you will know how to implement RecyclerView in Android using Kotlin . Before moving further let us know about RecyclerView. A RecyclerView is an advanced version of ListView with improved performance. When you have a long list of items to show you can use RecyclerView. It has the ability to reuse its views. In RecyclerView when the View goes out of the screen or not visible to the user it won't destroy it, it will reuse these views. This feature helps in reducing power consumption and providing more responsiveness to the application. Now let's see how to implement RecyclerView using Kotlin.
Step-by-Step Implementation
Step 1: Create a New Project
To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio.
Step 2: Go to activity_main.xml and add the following code
Add RecyclerView to activity_main.xml you can add it from the drag and drop from the design section or you can add it manually by writing some initial characters of RecyclerView then the IDE will give you suggestions for RecyclerView then select RecyclerView it will automatically add it to your layout file.
activity_main.xml:
XML <?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:id="@+id/main" android:layout_width="match_parent" android:layout_height="match_parent" tools:context=".MainActivity"> <androidx.recyclerview.widget.RecyclerView android:id="@+id/recyclerview" android:layout_width="match_parent" android:layout_height="match_parent" tools:listitem="@layout/card_view_design" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> </androidx.constraintlayout.widget.ConstraintLayout>
Design UI:
Step 3: Create a New Layout Resource File
Now create a new Layout Resource File which will be used to design our CardView layout. Go to app > res > layout > [right-click] > New > Layout Resource File and name that file as card_view_design and add the code provided below. In this file, you can design the layout to show it into the RecyclerView.
card_view_design.xml:
XML <?xml version="1.0" encoding="utf-8"?> <com.google.android.material.card.MaterialCardView 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:layout_margin="16dp"> <androidx.constraintlayout.widget.ConstraintLayout android:layout_width="match_parent" android:layout_height="wrap_content" android:orientation="horizontal" android:padding="8dp"> <ImageView android:id="@+id/imageview" android:layout_width="100dp" android:layout_height="100dp" android:layout_marginStart="16dp" android:layout_marginTop="8dp" android:layout_marginBottom="8dp" android:src="@drawable/gfg_logo" app:layout_constraintBottom_toBottomOf="parent" app:layout_constraintStart_toStartOf="parent" app:layout_constraintTop_toTopOf="parent" /> <TextView android:id="@+id/textView" android:layout_width="wrap_content" android:layout_height="wrap_content" android:layout_marginStart="32dp" android:text="Item" android:textSize="20sp" android:textStyle="bold" app:layout_constraintBottom_toBottomOf="@+id/imageview" app:layout_constraintEnd_toEndOf="parent" app:layout_constraintHorizontal_bias="0.0" app:layout_constraintStart_toEndOf="@+id/imageview" app:layout_constraintTop_toTopOf="@+id/imageview" /> </androidx.constraintlayout.widget.ConstraintLayout> </com.google.android.material.card.MaterialCardView>
Design UI:
Step 4: Create a new Kotlin class
Go to app > java > {package name} > [right-click] > New > Kotlin class/file and choose Data class from the list. Name that file as Item and then click on OK. This file will hold the information of every item which you want to show in your RecyclerView.
Item.kt:
Kotlin package org.geeksforgeeks.demo data class Item( val image: Int, val text: String )
Step 5: Create Adapter Class
Go to app > java > {package-name} > [right-click] > New > Kotlin class/file and name that file as Adapter and then click on OK. After this add the code provided below. Comments are added inside the code to understand the code in more detail.
This class contains some important functions to work with the RecyclerView these are as follows:
- onCreateViewHolder(): This function sets the views to display the items.
- onBindViewHolder(): This function is used to bind the list items to our widgets such as TextView, ImageView, etc.
- getItemCount(): It returns the count of items present in the list.
Adapter.kt:
Kotlin package org.geeksforgeeks.demo import android.view.LayoutInflater import android.view.View import android.view.ViewGroup import android.widget.ImageView import android.widget.TextView import androidx.recyclerview.widget.RecyclerView class Adapter(private val list: List<Item>) : RecyclerView.Adapter<Adapter.ViewHolder>() { // create new views override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): ViewHolder { // inflates the card_view_design view // that is used to hold list item val view = LayoutInflater.from(parent.context) .inflate(R.layout.card_view_design, parent, false) return ViewHolder(view) } // binds the list items to a view override fun onBindViewHolder(holder: ViewHolder, position: Int) { val item = list[position] // sets the image to the imageview from our itemHolder class holder.imageView.setImageResource(item.image) // sets the text to the textview from our itemHolder class holder.textView.text = item.text } // return the number of the items in the list override fun getItemCount(): Int { return list.size } // Holds the views for adding it to image and text class ViewHolder(view: View) : RecyclerView.ViewHolder(view) { val imageView: ImageView = itemView.findViewById(R.id.imageview) val textView: TextView = itemView.findViewById(R.id.textView) } }
Step 6: Working with the MainActivity.kt
Go to the MainActivity.kt file and refer to the following code. Below is the code for the MainActivity.kt file. Comments are added inside the code to understand the code in more detail.
MainActivity.kt:
Kotlin package org.geeksforgeeks.demo import android.os.Bundle import androidx.appcompat.app.AppCompatActivity import androidx.recyclerview.widget.LinearLayoutManager import androidx.recyclerview.widget.RecyclerView class MainActivity : AppCompatActivity() { override fun onCreate(savedInstanceState: Bundle?) { super.onCreate(savedInstanceState) setContentView(R.layout.activity_main) // getting the recyclerview by its id val recyclerview: RecyclerView = findViewById(R.id.recyclerview) // this creates a vertical layout Manager recyclerview.layoutManager = LinearLayoutManager(this) // ArrayList of class ItemsViewModel val data = ArrayList<Item>() // This loop will create 20 Views containing // the image with the count of view for (i in 1..20) { data.add(Item(R.drawable.gfg_logo, "Item $i")) } // This will pass the ArrayList to our Adapter val adapter = Adapter(data) // Setting the Adapter with the recyclerview recyclerview.adapter = adapter } } Output: