RecyclerView - How to implement RecyclerView in Android using Kotlin.

Last updated Dec 14, 2021


In this example, you will know how to implement RecyclerView in Android using Kotlin. RecyclerView is a more advanced and adaptable version of the listview and gridview. It's a container for presenting large amounts of data sets in a way that allows them to be browsed quickly while limiting the number of views. It has the ability to reuse its views. 

With RecyclerView we can arrange the items in Vertical and horizontal directions using RecyclerView LayoutManager

Implementation:

Create a new Project in android studio.

Go to File > New > New Project > Empty Activity > Next > Enter Name > Select Language Kotlin > Finish

 

Add the recyclerview and cardview dependency to build.gradle(app)

implementation 'androidx.recyclerview:recyclerview:1.2.0'


 Add CardView Dependency if needed (No need to add In latest version of android studio)

implementation 'androidx.cardview:cardview:1.0.0'

 

Go to activity_recycler_view.xml file and change the constraint layout to Linear Layout as follows:

    <LinearLayout 
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">  
    </LinearLayout>    

 

Add recyclerview widget inside LinearLayout.

 

      <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
      />

 

Create a new layout resource file and add the following code 

app > res > layout > new > layout resource file > enter name (cardview_layout.xml) > ok

 

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:layout_margin="10dp"
    app:cardElevation="6dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="5dp">

        <ImageView
            android:id="@+id/imageview"
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:src="@drawable/android"
            android:scaleType="centerCrop"
            />

        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="10dp"
            android:layout_marginLeft="15dp"
            android:text="Android"
            android:textSize="20sp"
            android:textStyle="bold" />

    </LinearLayout>

</androidx.cardview.widget.CardView>

 

Create a new Kotlin class for model 

 

app > java > package name > right-click > New > Kotlin class/file > enter name > OK


This file will hold the information of every item which you want to show in your RecyclerView.
 

class RecyclerModel(val image : Int, val text: String) {

}

 

Create a adapter class

app > java > package name > right-click > New > Kotlin class/file > enter name > ok

 

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.
 

 

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 RecyclerAdapter(private val dataList: List) : RecyclerView.Adapter() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerAdapter.ViewHolder {
        val view = LayoutInflater.from(parent.context)
            .inflate(R.layout.card_view_layout, parent, false)
        return ViewHolder(view)
    }

    override fun onBindViewHolder(holder: RecyclerAdapter.ViewHolder, position: Int) {
        val recyclerModel = dataList[position]

        // Image set to the imageview widget
        holder.imageView.setImageResource(recyclerModel.image)

        // Text set to the textview widget
        holder.textView.text = recyclerModel.text
    }

    override fun getItemCount(): Int {
        return dataList.size
    }
    class ViewHolder(ItemView: View) : RecyclerView.ViewHolder(ItemView) {
        val imageView: ImageView = itemView.findViewById(R.id.imageview)
        val textView: TextView = itemView.findViewById(R.id.textView)
    }

}

 

Go to RecyclerViewActivity.kt file and add the following code

val recyclerview = findViewById(R.id.recyclerview)

 recyclerview.layoutManager = LinearLayoutManager(this)
  val data = ArrayList()

    for (i in 1..12) {
            data.add(RecyclerModel(R.drawable.android, "Android" + i))
        }


     val adapter = RecyclerAdapter(data)

   recyclerview.adapter = adapter

 

Now run the app in your emulator, and get the following output.


OUTPUT:
 

 Complete source code of RecyclerView in android:

 activity_recycler_view.xml file

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".RecyclerViewActivity">

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />
</LinearLayout>

RecyclerViewActivity.kt file

 import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import androidx.recyclerview.widget.LinearLayoutManager
import androidx.recyclerview.widget.RecyclerView

class RecyclerViewActivity : AppCompatActivity() {
    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_recycler_view)
        val recyclerview = findViewById(R.id.recyclerview)

        // Used for vertical linearlayout view
        recyclerview.layoutManager = LinearLayoutManager(this)

        // ArrayList of class RecyclerModel
        val data = ArrayList()

        // This loop will create 12 Views containing
        // the image with the count of view
        for (i in 1..12) {
            data.add(RecyclerModel(R.drawable.android, "Android" + i))
        }

        // This will pass the ArrayList to our Adapter
        val adapter = RecyclerAdapter(data)

        // Setting the Adapter with the recyclerview
        recyclerview.adapter = adapter

    }
}

 

card_view_layout.xml file

<?xml version="1.0" encoding="utf-8"?>
<androidx.cardview.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="50dp"
    android:layout_margin="10dp"
    app:cardElevation="6dp">

    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:orientation="horizontal"
        android:padding="5dp">

        <ImageView
            android:id="@+id/imageview"
            android:layout_width="40dp"
            android:layout_height="40dp"
            android:src="@drawable/android"
            android:scaleType="centerCrop"
            />

        <TextView
            android:id="@+id/textView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_marginStart="10dp"
            android:layout_marginLeft="15dp"
            android:text="Android"
            android:textSize="20sp"
            android:textStyle="bold" />

    </LinearLayout>

</androidx.cardview.widget.CardView>

 

RecyclerModel.kt file

class RecyclerModel(val image : Int, val text: String) {

}

 

RecyclerAdapter.kt file 

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 RecyclerAdapter(private val dataList: List) : RecyclerView.Adapter() {
    override fun onCreateViewHolder(parent: ViewGroup, viewType: Int): RecyclerAdapter.ViewHolder {
        val view = LayoutInflater.from(parent.context)
            .inflate(R.layout.card_view_layout, parent, false)
        return ViewHolder(view)
    }

    override fun onBindViewHolder(holder: RecyclerAdapter.ViewHolder, position: Int) {
        val recyclerModel = dataList[position]

        // Image set to the imageview widget
        holder.imageView.setImageResource(recyclerModel.image)

        // Text set to the textview widget
        holder.textView.text = recyclerModel.text
    }

    override fun getItemCount(): Int {
        return dataList.size
    }
    class ViewHolder(ItemView: View) : RecyclerView.ViewHolder(ItemView) {
        val imageView: ImageView = itemView.findViewById(R.id.imageview)
        val textView: TextView = itemView.findViewById(R.id.textView)
    }

}

 

build.gradle(app) file

plugins {
    id 'com.android.application'
    id 'kotlin-android'
}

android {
    compileSdk 31

    defaultConfig {
        applicationId "com.nishajain.kotinexamples"
        minSdk 21
        targetSdk 31
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }
}

dependencies {

    implementation 'androidx.core:core-ktx:1.7.0'
    implementation 'androidx.appcompat:appcompat:1.4.0'
    implementation 'com.google.android.material:material:1.4.0'
    implementation 'androidx.constraintlayout:constraintlayout:2.1.2'
    testImplementation 'junit:junit:4.+'
    androidTestImplementation 'androidx.test.ext:junit:1.1.3'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0'
    implementation 'androidx.recyclerview:recyclerview:1.2.0'
}

 

Conclusion:  We have covered how to add RecyclerView in Android using kotlin language.

 


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