DatePicker in Android

 <?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:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity"
    tools:ignore="HardcodedText">

    <androidx.appcompat.widget.AppCompatButton
        android:id="@+id/btnopen"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="20dp"
        android:layout_marginTop="84dp"
        android:visibility="visible"
        android:background="@drawable/round_corner_border"
        android:text="Click open Calendar"
        android:textAllCaps="false"
        android:textColor="@color/white"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <androidx.appcompat.widget.AppCompatTextView
        android:id="@+id/txtdataandtime"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="48dp"
        android:textSize="50sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintHorizontal_bias="0.498"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/btnopen" />

 </androidx.constraintlayout.widget.ConstraintLayout>

 import android.annotation.SuppressLint
 import android.app.DatePickerDialog
 import android.os.Bundle
 import android.view.View
 import androidx.appcompat.app.AppCompatActivity
 import androidx.appcompat.widget.AppCompatButton
 import androidx.appcompat.widget.AppCompatTextView
 import java.util.Calendar

 class MainActivity : AppCompatActivity() {
     @SuppressLint("MissingInflatedId")
     override fun onCreate(savedInstanceState: Bundle?) {
         super.onCreate(savedInstanceState)
         setContentView(R.layout.activity_main)
         val btnopen = findViewById<View>(R.id.btnopen) as AppCompatButton
         val txtdataandtime = findViewById<View>(R.id.txtdataandtime) as AppCompatTextView
     
        btnopen.setOnClickListener {
            opendatatimepicker(txtdataandtime)
        }

    }

    fun opendatatimepicker(txtcalendar: AppCompatTextView) {
        val c = Calendar.getInstance()
        val year = c.get(Calendar.YEAR)
        val month = c.get(Calendar.MONTH)
        val day = c.get(Calendar.DAY_OF_MONTH)
        val datePickerDialog = DatePickerDialog(
            this,
            { view, year, monthOfYear, dayOfMonth ->

                txtcalendar.text =
                    (dayOfMonth.toString() + "-" + (monthOfYear + 1) + "-" + year)
            },

             year,
             month,
             day
         )

         datePickerDialog.show()
     }
 }