android kotlin - DatePickerDialog example

MainActivity.kt

package com.cfsuman.kotlintutorials

import android.content.Context
import android.os.Bundle
import android.widget.Button
import androidx.appcompat.app.AppCompatActivity


class MainActivity : AppCompatActivity() {
    private lateinit var context: Context

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)

        // Get the widgets reference from XML layout
        val button = findViewById<Button>(R.id.button)


        // Set a click listener for button widget
        button.setOnClickListener{
            // Initialize a new DatePickerFragment
            val datePickerFragment = DatePickerFragment()

            // Show the date picker dialog
            datePickerFragment.show(
                supportFragmentManager,
                "Date Picker"
            )
        }
    }
}

DatePickerFragment.kt

package com.cfsuman.kotlintutorials

import android.app.DatePickerDialog
import android.app.Dialog
import android.os.Bundle
import android.widget.TextView
import android.widget.DatePicker
import androidx.fragment.app.DialogFragment
import java.text.DateFormat
import java.util.Calendar


class DatePickerFragment : DialogFragment(),
    DatePickerDialog.OnDateSetListener {

    private lateinit var calendar:Calendar

    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
        // Initialize a calendar instance
        calendar = Calendar.getInstance()

        // Get the system current date
        val year = calendar.get(Calendar.YEAR)
        val month = calendar.get(Calendar.MONTH)
        val day = calendar.get(Calendar.DAY_OF_MONTH)

        // Initialize a new date picker dialog and return it
        return DatePickerDialog(
            requireActivity(), // Context
            // Put 0 to system default theme or remove this parameter
            this, // DatePickerDialog.OnDateSetListener
            year, // Year
            month, // Month of year
            day // Day of month
        )
    }


    // When date set and press ok button in date picker dialog
    override fun onDateSet(
        view: DatePicker, year: Int, month: Int, day: Int) {
        // Display the selected date in text view
        requireActivity().findViewById<TextView>(R.id.textView)
            .text = "Selected date : " + formatDate(year,month,day)
    }


    // Custom method to format date
    private fun formatDate(year:Int, month:Int, day:Int):String{
        // Create a Date variable/object with user chosen date
        calendar.set(year, month, day, 0, 0, 0)
        val chosenDate = calendar.time

        // Format the date picker selected date
        val df = DateFormat.getDateInstance(DateFormat.MEDIUM)
        return df.format(chosenDate)
    }
}

activity_main.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"
    android:id="@+id/rootLayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:padding="24dp"
    android:background="#F8F8F8">

    <TextView
        android:id="@+id/textView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_marginTop="32dp"
        android:padding="16dp"
        android:fontFamily="sans-serif"
        android:textSize="24sp"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/button" />

    <Button
        android:id="@+id/button"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Show DatePicker Dialog"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</androidx.constraintlayout.widget.ConstraintLayout>