In this article, we will learn how to create android NumberPicker programmatically in Kotlin. We will go through various steps that explains how to create NumberPicker and add it in kotlin file, use different attributes to customise it etc. in any android application. For example, how to set text in NumberPicker programmatically, how to set id of NumberPicker, how to capitalise text of NumberPicker dynamically etc. We will get answer to all such questions in this post.

Learn to use Different Attributes of NumberPicker in XML File to Customize it.

Output

Tutorialwing Kotlin Dynamic NumberPicker Integer Output

Tutorialwing Kotlin Dynamic NumberPicker String Output

Getting Started

We can define android NumberPicker widget as below –

NumberPicker is a widget that allows us to select a number from predefined range.

Now, how do we use NumberPicker in android application ?

Before we move ahead, we need to setup for viewBinding to access NumberPicker in Kotlin file without using findViewById() method.

Setup ViewBinding

Add viewBinding true in app/build.gradle file.

 
 android { 
 	// OTHER CODE... 
 	buildFeatures { 
 		viewBinding true 
 	} 
 } 
 

Now, set content in activity using view binding.
Open MainActivity.kt file and write below code in it.

 
 class MainActivity : AppCompatActivity() { 
 	
 	private lateinit var binding: ActivityMainBinding 
 	
 	override fun onCreate(savedInstanceState: Bundle?) { 
 		super.onCreate(savedInstanceState) 
 		binding = ActivityMainBinding.inflate(layoutInflater) 
 		val view = binding.root 
 		setContentView(view) 
 	} 
 } 
 

Now, we can access view in Kotlin file without using findViewById() method.

Since we have a new project, we will modify the xml and class file to use NumberPicker programmatically in kotlin. Please follow the steps below.

2. Modify Values Folder

Open res/values/strings.xml file. Add below code into it.

<resources>
    <string name="app_name">DynamicNumberPicker</string>
</resources>

Other values folders have not been changed. So, we are not going to mention it here.

3. Modify Layout Folder

Open res/layout/activity_main.xml file. Add below code into it.

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    android:id="@+id/rootContainer"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:gravity="center"
    android:orientation="vertical">

</LinearLayout>

Note that LinearLayout has id rootContainer. In Kotlin file, we will create NumberPicker Dynamically and add it into this LinearLayout having id rootContainer.

4. Create Android NumberPicker programmatically in Kotlin

NumberPicker widget can accepts two types of data. They are –

• a. Integer values.
• b. Array of String values.

Now, we will see how we can provide each data types to the numberPicker.

Show Integer Values in NumberPicker

Open src/main/java/com.tutorialwing.dynamicnumberpicker/MainActivity.kt file. Then, add below code into it.

package com.tutorialwing.dynamicnumberpicker

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.ViewGroup
import android.widget.LinearLayout
import android.widget.NumberPicker
import android.widget.Toast
import com.tutorialwing.dynamicnumberpicker.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

	private lateinit var binding: ActivityMainBinding

	override fun onCreate(savedInstanceState: Bundle?) {
		super.onCreate(savedInstanceState)
		binding = ActivityMainBinding.inflate(layoutInflater)
		val view = binding.root
		setContentView(view)

		setupNumberPicker()
	}

	private fun setupNumberPicker() {
		val numberPicker = NumberPicker(this)
		val layoutParams = LinearLayout.LayoutParams(
			ViewGroup.LayoutParams.MATCH_PARENT,
			ViewGroup.LayoutParams.WRAP_CONTENT
		)
		numberPicker.layoutParams = layoutParams

		numberPicker.minValue = 0
		numberPicker.maxValue = 10
		numberPicker.wrapSelectorWheel = true
		numberPicker.setOnValueChangedListener { picker, oldVal, newVal ->
			val text = "Changed from $oldVal to $newVal"
			Toast.makeText(this@MainActivity, text, Toast.LENGTH_SHORT).show()
		}
		binding.rootContainer.addView(numberPicker)
	}
}

Here, We have created numberPicker programmatically in kotlin file. After that, we have configured numberPicker to show range of integer values. minValue is used to set minimum value in range. maxValue is used to set maximum value in range. wrapSelectorWheel is used to specify whether we want to show start value of range if we have reached to end. We have also defined a listener that displays a toast message whenever there is change in value selection in numberPicker. Finally, we have added numberPicker widget in linearLayout.

Finally, when you run the application, you will get output as shown above.

Tutorialwing Kotlin Dynamic NumberPicker Integer Output

Show String Values in NumberPicker

Open src/main/java/com.tutorialwing.dynamicnumberpicker/MainActivity.kt file. Then, add below code into it.

package com.tutorialwing.dynamicnumberpicker

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.ViewGroup
import android.widget.LinearLayout
import android.widget.NumberPicker
import android.widget.Toast
import com.tutorialwing.dynamicnumberpicker.databinding.ActivityMainBinding

class MainActivity : AppCompatActivity() {

	private lateinit var binding: ActivityMainBinding

	override fun onCreate(savedInstanceState: Bundle?) {
		super.onCreate(savedInstanceState)
		binding = ActivityMainBinding.inflate(layoutInflater)
		val view = binding.root
		setContentView(view)

		setupNumberPickerWithStringValues()
	}

	private fun setupNumberPickerWithStringValues() {
		val numberPicker = NumberPicker(this)
		val layoutParams = LinearLayout.LayoutParams(
			ViewGroup.LayoutParams.MATCH_PARENT,
			ViewGroup.LayoutParams.WRAP_CONTENT
		)
		numberPicker.layoutParams = layoutParams

		val values = arrayOf("Blue", "Magenta", "Yellow", "Red", "Pink", "White", "Green", "Violet")
		numberPicker.minValue = 0
		numberPicker.maxValue = values.size - 1
		numberPicker.displayedValues = values
		numberPicker.wrapSelectorWheel = true
		numberPicker.setOnValueChangedListener { picker, oldVal, newVal ->
			val text = "Changed from " + values[oldVal] + " to " + values[newVal]
			Toast.makeText(this@MainActivity, text, Toast.LENGTH_SHORT).show()
		}

		binding.rootContainer.addView(numberPicker)
	}
}

Here, we have created numberPicker programmatically in kotlin file. After that, we have configured it to show array of string values. Variable values represents array of string values that we will provide to numberPicker. We have provided data to the numberPicker using displayedValues attribute.

Finally, when you run the application, you will get output as shown above.

Tutorialwing Kotlin Dynamic NumberPicker String Output

Now, Let’s check how to use different attributes of NumberPicker to customize it dynamically –

Set Id of NumberPicker

Follow steps below to set id of NumberPicker programmatically –

• Create ids.xml file in res/values folder. Then, add below code into it –

  <?xml version="1.0" encoding="utf-8"?>
  <resources>
      <item type="id" name="numberPicker_ID" />
  </resources>
  

• Now, we can set id of NumberPicker dynamically, in MainActivity.kt file, as –

  numberPicker.id = R.id.numberPicker_ID  // NumberPicker
  

  Here, we have set id of NumberPicker using property access syntax – numberPicker.id

Learn to Set ID of NumberPicker Using XML Attribute

Set Width and Height of NumberPicker

We use layoutParams to set width and height of any View programmatically. In this article, we have added NumberPicker in LinearLayout. So, we will define LayoutParams as below –

numberPicker.layoutParams = LinearLayout.LayoutParams(
	ViewGroup.LayoutParams.WRAP_CONTENT,
	ViewGroup.LayoutParams.WRAP_CONTENT
)

Here, we have set width and height as WRAP_CONTENT. Some of possible values for width and height are –

• WRAP_CONTENT: Sets value of width or height depending on text inside it.
• MATCH_PARENT: Sets value of width of height depending on width or height of parent layout . i.e. width or height of NumberPicker will be same as width or height of parent layout.
• Fixed Value: Sets width or height as per value provided.

Learn to Set Width or Height of NumberPicker Using XML Attribute

Set Padding of NumberPicker

Follow steps below to set padding of NumberPicker Dynamically –

• If there is no dimens.xml file, create dimens.xml file in res/values folder. Then, add below code in it –

  <?xml version="1.0" encoding="utf-8"?>
  <resources>
      <dimen name="text_padding">16dp</dimen>
  </resources>
  

• Now, we can set padding of NumberPicker dynamically, in MainActivity.kt file, as –

  val padding = resources.getDimension(R.dimen.text_padding).toInt()
  numberPicker.setPadding(padding, padding, padding, padding)
  

  Here, we have accessed dimension defined in dimens.xml using getDimension() method. Then, set padding of NumberPicker using setPadding() method.

Learn to Set Padding of NumberPicker Using XML Attribute

Set Margin of NumberPicker

Follow steps below to set margin of NumberPicker Dynamically –

• If there is no dimens.xml file, create dimens.xml file in res/values folder. Then, add below code in it –

  <?xml version="1.0" encoding="utf-8"?>
  <resources>
      <dimen name="text_margin">16dp</dimen>
  </resources>
  

• Now, we can set margin of NumberPicker dynamically, in MainActivity.kt file, as –

  val margin = resources.getDimension(R.dimen.text_margin).toInt()
  val layoutParams = LinearLayout.LayoutParams(
  	ViewGroup.LayoutParams.WRAP_CONTENT,
  	ViewGroup.LayoutParams.WRAP_CONTENT
  )
  layoutParams.setMargins(margin, margin, margin, margin)
  numberPicker.layoutParams = layoutParams
  

  Here, we have accessed dimension defined in dimens.xml using getDimension() method. Then, we have defined layoutParams, set margin to layoutParams. After that, set layoutParams to NumberPicker.

Learn to Set Margin of NumberPicker Using XML Attribute

Set Background of NumberPicker

Follow steps below to set background of NumberPicker programmatically –

• If there is no colors.xml file, create colors.xml file in res/values folder. Then, add below code in it –

  <?xml version="1.0" encoding="utf-8"?>
  <resources>
      <color name="purple_200">#FFBB86FC</color>
  </resources>
  

• Now, we can set background of NumberPicker dynamically, in MainActivity.kt file, as –

  val color = ContextCompat.getColor(this, R.color.purple_200)
  numberPicker.setBackgroundColor(color)
  

  Here, we used setBackgroundColor() method to set background color in numberPicker.

Learn to Set Background of NumberPicker Using XML Attribute

Set Visibility of NumberPicker

We can set visibility of NumberPicker programmatically as –

numberPicker.visibility = View.VISIBLE

Here, we have set visibility of NumberPicker using numberPicker.visibility attribute. Visibility can be of three types – gone, visible and invisible.
Learn to Set Visibility of NumberPicker Using XML Attribute

That’s end of tutorial on NumberPicker Programmatically in Kotlin With Example.