Create An Android RatingBar Programmatically in Kotlin

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

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

Output

Tutorialwing Android Dynamic RatingBar Output Android RatingBar Programmatically in Kotlin

Tutorialwing Android Dynamic RatingBar Output

Getting Started

We can define android RatingBar widget as below –

Android RatingBar is a widget extended from SeekBar and ProgressBar that shows a rating in stars. The user can either touch or drag the arrow to set the rating.

Now, how do we use RatingBar 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 DynamicRatingBar. 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 RatingBar 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 RatingBar 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">DynamicRatingBar</string>
    <string name="submit">Submit</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
    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
        android:id="@+id/rootContainer"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:orientation="vertical">

    </LinearLayout>

    <Button
        android:id="@+id/btnSubmit"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="@string/submit"/>

</LinearLayout>

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

4. Create Android RatingBar programmatically in Kotlin

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

package com.tutorialwing.dynamicratingbar

import androidx.appcompat.app.AppCompatActivity
import android.os.Bundle
import android.view.ViewGroup
import android.widget.LinearLayout
import android.widget.RatingBar
import android.widget.Toast
import com.tutorialwing.dynamicratingbar.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)

		setupRatingBar()
	}

	private fun setupRatingBar() {
		// Create rating bar programmatically...
		val ratingBar = RatingBar(this)
		val layoutParams = LinearLayout.LayoutParams(
			ViewGroup.LayoutParams.MATCH_PARENT,
			ViewGroup.LayoutParams.WRAP_CONTENT
		)
		layoutParams.setMargins(30, 30, 30, 30)
		ratingBar.layoutParams = layoutParams
		ratingBar.stepSize = 0.5.toFloat()

		// Add RatingBar to LinearLayout
		binding.rootContainer.addView(ratingBar)

		binding.btnSubmit.setOnClickListener {
			val msg = ratingBar.rating.toString()
			Toast.makeText(this@MainActivity, msg, Toast.LENGTH_SHORT).show()
		}
	}
}

In MainActivity.kt file, we have defined a ratingBar widget in the application. Then, we have set it’s params, step and margin. After that, we have added this ratingBar widget in linearLayout. At last, we have set a click listener to show toast message, displaying currently selected rating in the ratingBar, whenever it is clicked.

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

Tutorialwing Android Dynamic RatingBar Output Android RatingBar Programmatically in Kotlin

Tutorialwing Android Dynamic RatingBar Output

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

Set Id of RatingBar

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

    ratingBar.id = R.id.ratingBar_ID  // RatingBar
    

    Here, we have set id of RatingBar using property access syntax – ratingBar.id

Learn to Set ID of RatingBar Using XML Attribute

Set Width and Height of RatingBar

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

ratingBar.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 RatingBar 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 RatingBar Using XML Attribute

Set Padding of RatingBar

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

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

Learn to Set Padding of RatingBar Using XML Attribute

Set Margin of RatingBar

Follow steps below to set margin of RatingBar 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 RatingBar 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)
    ratingBar.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 RatingBar.

Learn to Set Margin of RatingBar Using XML Attribute

Set Background of RatingBar

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

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

Learn to Set Background of RatingBar Using XML Attribute

Set Visibility of RatingBar

We can set visibility of RatingBar programmatically as –

ratingBar.visibility = View.VISIBLE

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

Set Text of RatingBar

Follow steps below to set text of RatingBar 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 RatingBar dynamically, in MainActivity.kt file, as –
    ratingBar.text = getString(R.string.click_on_me)
    

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

Learn to Set Text of RatingBar Using XML Attribute

Set Color of Text of RatingBar

Follow steps below to set color of text of RatingBar 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 RatingBar dynamically, in MainActivity.kt file, as –
    val textColor = ContextCompat.getColor(this, R.color.black)
    ratingBar.setTextColor(textColor)
    

    Here, we used setTextColor() method to set color of RatingBar of ratingBar.

Learn to Set Color of RatingBar Using XML Attribute

Set Gravity of RatingBar

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

ratingBar.gravity = Gravity.CENTER

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

ratingBar.gravity = Gravity.CENTER_HORIZONTAL or Gravity.BOTTOM

Here, we have applied multiple gravity values, in Kotlin, to RatingBar. In above case, text will be aligned as horizontally centered to bottom.
Learn to Set Margin of RatingBar 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 ratingBar.isAllCaps attributes to set text in uppercase or normal. If it is true, text will be set in uppercase.

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

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

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

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

    Above code will set text, “Hello Tutorialwing”, to RatingBar 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 ratingBar.

Learn to Set Text in Uppercase or Lowercase Using XML Attribute

Set Size of Text in RatingBar

Follow steps below to set size of RatingBar programmatically using ratingBar.textSize attribute –

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

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

Learn to Set Size of Text in RatingBar Using XML Attribute

Set Style (Bold/italic) of Text in RatingBar

We can set textStyle of RatingBar programmatically as –

ratingBar.typeface = Typeface.DEFAULT_BOLD;

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

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

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

Learn to Set Typeface of RatingBar Using XML Attribute

Set Letter Spacing of Text in RatingBar

Follow steps below to set letter spacing of RatingBar programmatically –

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

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

Learn to Set Letter Spacing of RatingBar Using XML Attribute

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