How to use Calendar Widget using the CalendarView class in Android App using Kotlin?

This example demonstrates how to use Calendar Widget using the CalendarView class in Android App using Kotlin.

Step 1 − Create a new project in Android Studio, go to File ⇒ New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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:padding="4dp"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/dateView"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="20dp"
      android:text="Set the Date"
      android:textColor="@android:color/background_dark"
      android:textStyle="bold" />
   <CalendarView
      android:id="@+id/calender"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      android:layout_below="@id/dateView"
      android:layout_centerInParent="true"
      android:layout_marginTop="20dp">
   </CalendarView>
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.kt

import android.os.Bundle
import android.widget.CalendarView
import android.widget.CalendarView.OnDateChangeListener
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity() {
   lateinit var calendarView: CalendarView
   lateinit var dateView: TextView
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "Kotlin"
      calendarView = findViewById(R.id.calender)
      dateView = findViewById(R.id.dateView)
      calendarView.setOnDateChangeListener(OnDateChangeListener { _, year, month, dayOfMonth −>
         val date = dayOfMonth.toString() + "−" + (month + 1) + "−" + year
         dateView.text = date
      })
   }
}

Step 4 − Add the following code to androidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.example.q11">
   <application
      android:allowBackup="true"
      android:icon="@mipmap/ic_launcher"
      android:label="@string/app_name"
      android:roundIcon="@mipmap/ic_launcher_round"
      android:supportsRtl="true"
      android:theme="@style/AppTheme">
      <activity android:name=".MainActivity">
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
      </activity>
   </application>
</manifest>

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen