Dynamic DatePicker in Kotlin

Android DatePicker is a user interface control which is used to select the date by day, month and year in our Android application. DatePicker is used to ensure that users select a valid date.

In Android DatePicker has two modes, the first one shows the complete calendar and the second one shows the dates in spinner view. We can create a DatePicker control in two ways either manually in an XML file or create it in an Activity file programmatically. In this article, we will be learning how to implement a Date Picker programmatically in Kotlin.

Step by Step Implementation

Step 1: Create a new Android Project

To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio.

Note: Select Kotlin as the programming language.

Step 2: Modify activity_main.xml file

In this file, we use the LinearLayout, which is going to be accessed in the Kotlin file. Also set the attribute of the Layout like id, orientation and gravity etc.

activity_main.xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    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:id="@+id/main"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    android:gravity="center"
    tools:context=".MainActivity">

</LinearLayout>

Step 3: Create the DatePicker in MainActivity.kt file

First of all, we create a textview and the DatePicker widget.

val textView = TextView(this)
val datePicker = DatePicker(this)

we define a layout parameter for both the views and set them to the views

val layoutParams = LinearLayout.LayoutParams(
    ViewGroup.LayoutParams.WRAP_CONTENT,
    ViewGroup.LayoutParams.WRAP_CONTENT
)
layoutParams.setMargins(100)

datePicker.layoutParams = layoutParams
textView.layoutParams = layoutParams

then, we define the main layout and the two views to the layout

val linearLayout: LinearLayout = findViewById(R.id.main)
linearLayout.addView(datePicker)
linearLayout.addView(textView)

then, we define and get the current date, month and year

val today = Calendar.getInstance()
val currentDate = today.get(Calendar.DAY_OF_MONTH)
val currentMonth = today.get(Calendar.MONTH)
val currentYear = today.get(Calendar.YEAR)

Finally, we initialize the datepicker with the current date

datePicker.init(currentYear, currentMonth, currentDate) { view, year, month, day ->
    val month1 = month + 1
    val message = "$day - $month1 - $year"
    textView.text = message
}

MainActivity.kt:

package org.geeksforgeeks.demo

import android.os.Bundle
import android.view.ViewGroup
import android.widget.DatePicker
import android.widget.LinearLayout
import android.widget.TextView
import androidx.appcompat.app.AppCompatActivity
import androidx.core.view.setMargins
import java.util.Calendar

class MainActivity : AppCompatActivity() {

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

        // create textView programmatically
        val textView = TextView(this)
        
        // create DatePicker programmatically
        val datePicker = DatePicker(this)

        val layoutParams = LinearLayout.LayoutParams(
            ViewGroup.LayoutParams.WRAP_CONTENT,
            ViewGroup.LayoutParams.WRAP_CONTENT
        )
        layoutParams.setMargins(100)

        datePicker.layoutParams = layoutParams
        textView.layoutParams = layoutParams
        textView.textSize = 24f

        val linearLayout: LinearLayout = findViewById(R.id.main)
        linearLayout.addView(datePicker)
        linearLayout.addView(textView)

        val today = Calendar.getInstance()
        val currentDate = today.get(Calendar.DAY_OF_MONTH)
        val currentMonth = today.get(Calendar.MONTH)
        val currentYear = today.get(Calendar.YEAR)

        datePicker.init(currentYear, currentMonth, currentDate) { _, year, month, day ->
            val month1 = month + 1
            val message = "$day - $month1 - $year"
            textView.text = message
        }
    }
}

Output: