In this article, we will learn about android RatingBar using Kotlin. We will go through various example that demonstrates how to use different attributes of RatingBar. For example, …..

In this article, we will get answer to questions like –

• What is RatingBar?
• Why should we consider RatingBar while designing ui for any app?
• What are possibilities using RatingBar while designing ui? etc.

Let’s have a quick demo of things we want to cover in this tutorial –

Output

Tutorialwing Android 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

At first, we will create an application.
So, follow steps below to create any android project in Kotlin –

Newbie in Android ?

Some very important concepts (Recommended to learn before you move ahead)

• Install Android Studio
• Create New Project in Android Studio
• Android Project Structure
• Run / Debug / Test Android App

Before we move ahead, we need to setup for viewBinding to access Android RatingBar Using 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.

Using RatingBar in Kotlin

Follow steps below to use RatingBar in newly created project –

• Open res/values/strings.xml file. Then, add below code into it.

  <resources>
      <string name="app_name">RatingBar</string>
      <string name="submit">Submit</string>
  </resources>
  

• Open res/layout/activity_main.xml file. Then, add below code in it –

  <?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"
      xmlns:tools="http://schemas.android.com/tools"
      android:layout_width="match_parent"
      android:layout_height="match_parent"
      tools:context=".MainActivity">
  
      <RatingBar
          android:id="@+id/ratingBar"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:stepSize="0.5"
          app:layout_constraintBottom_toBottomOf="parent"
          app:layout_constraintLeft_toLeftOf="parent"
          app:layout_constraintRight_toRightOf="parent"
          app:layout_constraintTop_toTopOf="parent" />
  
      <Button
          android:id="@+id/btnSubmit"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:text="@string/submit"
          app:layout_constraintEnd_toEndOf="parent"
          app:layout_constraintStart_toStartOf="parent"
          app:layout_constraintTop_toBottomOf="@+id/ratingBar" />
  
  </androidx.constraintlayout.widget.ConstraintLayout>
  

  In activity_main.xml file, we have defined ratingBar and button widget. Notice the attribute android:stepSize=”0.5″ in RatingBar. This attribute is responsible to set steps in which value will increment/decrement while selecting the rating in the RatingBar. Attribute android:theme=”@style/RatingBar” is used to set theme/style in the ratingBar. You can also set your custom theme in it.

  Now, we will access button and ratingbar using kotlin file to perform some actions on them.

• We can also access it in Kotlin File, MainActivity.kt, as below –

  package com.tutorialwing.ratingbar
  
  import androidx.appcompat.app.AppCompatActivity
  import android.os.Bundle
  import android.widget.Toast
  import com.tutorialwing.ratingbar.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)
  
  		setClickListener()
  	}
  
  	private fun setClickListener() {
  		binding.btnSubmit.setOnClickListener {
  			val msg = binding.ratingBar.rating.toString()
  			Toast.makeText(this@MainActivity, msg, Toast.LENGTH_SHORT).show()
  		}
  	}
  }
  

  In MainActivity.kt file, we have accessed ratingBar and button widgets. Then, we have set click listener on button to show toast message, that displays selected rating in the ratingBar, whenever it is clicked.

Now, run the application. We will get output as below –

Tutorialwing Android RatingBar Output

Different Attributes of RatingBar in XML

Now, we will see how to use different attributes of Android RatingBar using Kotlin to customise it –

Set Id of RatingBar

Many a time, we need id of View to access it in kotlin file or create ui relative to that view in xml file. So, we can set id of RatingBar using android:id attribute like below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        />

Here, we have set id of RatingBar as ratingBar_ID using android:id=”” attribute. So, if we need to reference this RatingBar, we need to use this id – ratingBar_ID.
Learn to Set ID of RatingBar Dynamically

Set Width of RatingBar

We use android:layout_width=”” attribute to set width of RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        />

Width can be either “MATCH_PARENT” or “WRAP_CONTENT” or any fixed value (like 20dp, 30dp etc.).
Learn to Set Width of RatingBar Dynamically

Set Height of RatingBar

We use android:layout_height=”” attribute to set height of RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        />

Height can be either “MATCH_PARENT” or “WRAP_CONTENT” or any fixed value.
Learn to Set Height of RatingBar Dynamically

Set Padding of RatingBar

We use android:padding=”” attribute to set padding of RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:padding="10dp"
        />

Here, we have set padding of 10dp in RatingBar using android:padding=”” attribute.
Learn to Set Padding of RatingBar Dynamically

Set Margin of RatingBar

We use android:layout_margin=”” attribute to set margin of RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_margin="10dp"
        />

Here, we have set margin of 10dp in RatingBar using android:layout_margin=”” attribute.
Learn to Set Margin of RatingBar Dynamically

Set Background of RatingBar

We use android:background=”” attribute to set background of RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="#ff0000"
        />

Here, we have set background of color #ff0000 in RatingBar using android:background=”” attribute.
Learn to Set Background of RatingBar Dynamically

Set Visibility of RatingBar

We use android:visibility=”” attribute to set visibility of RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:visibility="gone"
        />

Here, we have set visibility of RatingBar using android:visiblity=”” attribute. Visibility can be of three types – gone, visible and invisible
Learn to Set Visibility of RatingBar Dynamically

Set Text of RatingBar

We use android:text=”” attribute to set text of RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        />

Here, we have set text (“Hello Tutorialwing”) in RatingBar using android:text=”” attribute.
Similarly, we can set any text using this attribute.
Learn to Set Text of RatingBar Dynamically

Set Color of Text in RatingBar

We use android:textColor=”” attribute to set color of text in RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        android:textColor="#ffffff"     
        />

Here, we have set color (#ffffff i.e. white) of text (“Hello Tutorialwing”) in RatingBar using android:textColor=”” attribute. Similarly, we can set any color using this attribute.
Learn to Set Color of RatingBar Dynamically

Set Gravity of RatingBar

We use android:gravity=”” attribute to set gravity of text in RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        android:gravity="center_horizontal"
        />

Here, we have set gravity of text in RatingBar using android:gravity=”” attribute. Attribute value can be – “center_horizontal”, “center”, “center_vertical” etc.
Learn to Set Gravity of RatingBar Dynamically

Set Text in Uppercase, Lowercase

If we need to show text of RatingBar in uppercase or lowercase etc.

Set text in uppercase

We can use android:textAllCaps=”true” attribute to set text in uppercase. We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        android:textAllCaps="true"
        />

Attribute android:textAllCaps=”true” sets text in uppercase. So, HELLO TUTORIALWING is set in RatingBar.

By default, false is set in this attribute. So, Whatever value is written in android:text=”” attribute, it will be set as it is. For example,

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        android:textAllCaps="false"
        />

Above code will set Hello Tutorialwing to RatingBar.

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 Dynamically

Set Size of Text in RatingBar

We use android:textSize=”” attribute to set size of text in RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        android:textSize="20sp"
        />

Here, we have set size of text in RatingBar using android:textSize=”” attribute.
Learn to Set Size of Text of RatingBar Dynamically

Set Style (Bold/italic) of Text in RatingBar

We use android:textStyle=”” attribute to set style (bold, italic etc.) of text in RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        android:textStyle="bold"
        />

Here, we have set style of text in RatingBar using android:textStyle=”” attribute. This attribute can take bold, italic or normal.
Learn to Set Style of Text of RatingBar Dynamically

Set Letter Spacing of Text in RatingBar

We use android:letterSpacing=”” attribute to set spacing between letters of text in RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        android:letterSpacing="1"
        />

Here, we have set spacing between letters of text in RatingBar using android:letterSpacing=”” attribute.
Learn to Set Letter Spacing of Text of RatingBar Dynamically

Set Typeface of Text in RatingBar

We use android:typeface=”” attribute to set typeface in RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        android:typeface="sans"
        />

Here, we have set typeface of text in RatingBar using android:typeface=”” attribute. This attribute can take values – “sans”, “normal”, “monospace” or “normal”.
Learn to Set Typeface of RatingBar Dynamically

Set fontFamily of Text in RatingBar

We use android:fontFamily=”” attribute to set fontFamily of text in RatingBar.
We can do it as below –

    <RatingBar
        android:id="@+id/ratingBar_ID"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello Tutorialwing"
        android:fontFamily="sans-serif"
        />

Here, we have set fontFamily (Here, sans-serif) of text in RatingBar using android:fontFamily=”sans-serif” attribute.

Till now, we have see how to use android RatingBar using Kotlin. We have also gone through different attributes of RatingBar to perform certain task. Let’s have a look at list of such attributes and it’s related task.

Different Attributes of Android RatingBar Widget

Below are the various attributes that are used to customise android RatingBar Widget. However, you can check the complete list of attributes of RatingBar in it’s official documentation site. Here, we are going to list some of the important attributes of this widget –

Some of the popular attributes of android RatingBar are –

Some of the popular attributes of android ratingBar inherited from AbsSeekBar are –

Some of the popular attributes of android ratingBar inherited from ProgressBar are –

Some of the popular attributes of android ratingBar inherited from View are –

We have seen different attributes of RatingBar and how to use it. If you wish to visit post to learn more about it

Thus, we have seen what is RatingBar, how can we use android RatingBar using Kotlin ? etc. We also went through different attributes of android RatingBar.