Create An Android Button Programmatically in Kotlin

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

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

Output

Tutorialwing - Android Button programmatically in Kotlin Create button dynamically in kotlin Create Android Button Widget

Tutorialwing – Android Button programmatically in Kotlin

Video Output

Getting Started

We can define android Button widget as below –

Android Button is an user interface that are used to perform some action when clicked or tapped.

Now, how do we use Button in android application ?

Creating New Project

Follow steps below to create any android project in Kotlin –

Step Description
1. Open Android Studio (Ignore if already done).
2. Go to File => New => New Project. This will open a new window. Then, under Phone and Tablet section, select Empty Activity. Then, click Next.
3. In next screen, select project name as DynamicButton. Then, fill other required details.
4. Then, clicking on Finish button creates new project.

Newbie in Android ?
Some very important concepts (Recommended to learn before you move ahead)

Before we move ahead, we need to setup for viewBinding to access Button 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 Button 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">DynamicButton</string>
    <string name="show_text">Show Text</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/rootLayout"
    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 rootLayout. In Kotlin file, we will create Button Dynamically and add it into this LinearLayout having id rootLayout.

4. Create Android Button programmatically in Kotlin

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

package com.tutorialwing.dynamicbutton

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.Gravity
import android.view.ViewGroup
import android.widget.Button
import android.widget.LinearLayout
import com.tutorialwing.dynamicbutton.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)

		addButton()
	}

	private fun addButton() {

		// Create Button programmatically.
		val button = Button(this)
		button.layoutParams = LinearLayout.LayoutParams(
			ViewGroup.LayoutParams.WRAP_CONTENT,
			ViewGroup.LayoutParams.WRAP_CONTENT
		)
		button.gravity = Gravity.CENTER
		button.text = getString(R.string.show_text)

		// Add Button to LinearLayout
		binding.rootLayout.addView(button)
	}
}

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

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

Set Id of Button

Follow steps below to set id of Button 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="TEXT_ID" />
    </resources>
    
  • Now, we can set id of Button dynamically, in MainActivity.kt file, as –

    button.id = R.id.TEXT_ID  // Button
    

    Here, we have set id of Button using property access syntax – button.id

Learn to Set ID of Button Using XML Attribute

Set Width and Height of Button

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

button.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 Button 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 Button Using XML Attribute

Set Padding of Button

Follow steps below to set padding of Button 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 Button dynamically, in MainActivity.kt file, as –
    val padding = resources.getDimension(R.dimen.text_padding).toInt()
    button.setPadding(padding, padding, padding, padding)
    

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

Learn to Set Padding of Button Using XML Attribute

Set Margin of Button

Follow steps below to set margin of Button 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 Button 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)
    button.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 Button.

Learn to Set Margin of Button Using XML Attribute

Set Background of Button

Follow steps below to set background of Button 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 Button dynamically, in MainActivity.kt file, as –
    val color = ContextCompat.getColor(this, R.color.purple_200)
    button.setBackgroundColor(color)
    

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

Learn to Set Background of Button Using XML Attribute

Set Visibility of Button

We can set visibility of Button programmatically as –

button.visibility = View.VISIBLE

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

Set Text of Button

Follow steps below to set text of Button programmatically –

  • If there is no strings.xml file, create strings.xml file in res/values folder. Then, add below code in it –
    <resources>
        <string name="click_on_me">Click on me</string>
    </resources>
    
  • Now, we can set text of Button dynamically, in MainActivity.kt file, as –
    button.text = getString(R.string.click_on_me)
    

    Here, we used button.text to set text in button.

Learn to Set Text of Button Using XML Attribute

Set Color of Text of Button

Follow steps below to set color of text of Button programmatically in Kotlin –

  • 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="black">#FF000000</color>
    </resources>
    
  • Now, we can set color of text of Button dynamically, in MainActivity.kt file, as –
    val textColor = ContextCompat.getColor(this, R.color.black)
    button.setTextColor(textColor)
    

    Here, we used setTextColor() method to set color of Button of button.

Learn to Set Color of Button Using XML Attribute

Set Gravity of Button

We can set gravity of text of Button programmatically in Kotlin as –

button.gravity = Gravity.CENTER

Here, we have set gravity of Button as center. So, all the text of Button will be center aligned.
We can also apply multiple gravity values as –

button.gravity = Gravity.CENTER_HORIZONTAL or Gravity.BOTTOM

Here, we have applied multiple gravity values, in Kotlin, to Button. In above case, text will be aligned as horizontally centered to bottom.
Learn to Set Margin of Button Using XML Attribute

Set Text in Uppercase or Lowercase

Follow steps below to set text in uppercase or lowercase programmatically as –

  • Set Text in Uppercase

    We use button.isAllCaps attributes to set text in uppercase or normal. If it is true, text will be set in uppercase.

    button.text = "Hello Tutorialwing"
    button.isAllCaps = true
    

    In Above case, “Hello Tutorialwing” will be set in Uppercase to Button. So, text will be “HELLO TUTORIALWING”.

  • By default, isAllCaps is false. So, whatever is written, text will be set as it is. For example,

    button.text = "Hello Tutorialwing"
    button.isAllCaps = false. // By default it is false. Written here for example.
    

    Above code will set text, “Hello Tutorialwing”, to Button without changing it to Uppercase.

    Actually, if isAllCaps is false, text is set as it is. It neither changes to uppercase nor lowercase.

    How do we set text in lowercase?

    Answer –

    • In xml file – write all the text in lowercase.
    • In kotlin file – take text as string. Then, convert it in lowercase. Then, set it to button.

Learn to Set Text in Uppercase or Lowercase Using XML Attribute

Set Size of Text in Button

Follow steps below to set size of Button programmatically using button.textSize attribute –

  • Open res/values/dimens.xml file. Then, add below font-size in it –
    <dimen name="text_size">16sp</dimen>
    
  • Now, using button.textSize attribute, we can set size of text dynamically as –

    button.textSize = resources.getDimension(R.dimen.text_margin)
    

Learn to Set Size of Text in Button Using XML Attribute

Set Style (Bold/italic) of Text in Button

We can set textStyle of Button programmatically as –

button.typeface = Typeface.DEFAULT_BOLD;

In above case, we have set textStyle as bold. So, text of Button will be displayed as bold letters.

If we want to preserve previous textStyle too, we can do it as –

button.setTypeface(button.typeface, Typeface.BOLD);

Learn to Set Typeface of Button Using XML Attribute

Set Letter Spacing of Text in Button

Follow steps below to set letter spacing of Button programmatically –

  • Open res/values/dimens.xml file. Then, add below dimension in it –
    <dimen name="text_letter_spacing">1dp</dimen>
    
  • We use button.letterSpacing attribute to set letter spacing of Button as below –

    button.letterSpacing = resources.getDimension(R.dimen.text_letter_spacing)
    

Learn to Set Letter Spacing of Button Using XML Attribute

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