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.
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Go to File > New > New Project > Empty Activity > Next > Enter Name > Select Language Kotlin > Finish
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Add the recyclerview and cardview dependency to build.gradle(app)
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implementation 'androidx.recyclerview:recyclerview:1.2.0'
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Add CardView Dependency if needed (No need to add In latest version of android studio)
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implementation 'androidx.cardview:cardview:1.0.0'
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Go to activity_recycler_view.xml file and change the constraint layout to Linear Layout as follows:
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<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>
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Add recyclerview widget inside LinearLayout.
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<androidx.recyclerview.widget.RecyclerView
android:id="@+id/recyclerview"
android:layout_width="match_parent"
android:layout_height="match_parent"
/>
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Create a new layout resource file and add the following code
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app > res > layout > new > layout resource file > enter name (cardview_layout.xml) > ok
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<?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>
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Create a new Kotlin class for model
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app > java > package name > right-click > New > Kotlin class/file > enter name > OK
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This file will hold the information of every item which you want to show in your RecyclerView.
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class RecyclerModel(val image : Int, val text: String) {
}
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Create a adapter class
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app > java > package name > right-click > New > Kotlin class/file > enter name > ok
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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.
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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)
}
}
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Go to RecyclerViewActivity.kt file and add the following code
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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
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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
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<?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>
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RecyclerViewActivity.kt file
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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
}
}
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card_view_layout.xml file
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<?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>
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RecyclerModel.kt file
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class RecyclerModel(val image : Int, val text: String) {
}
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RecyclerAdapter.kt file
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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)
}
}
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build.gradle(app) file
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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'
}
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Conclusion: We have covered how to add RecyclerView in Android using kotlin language.
