Hello Readers! In this post, we are going to learn about how to use android ratingBar using kotlin in any android application. We will also learn about different attributes of android ratingBar widget that can be used to customise this widget.

Output

Tutorialwing Android RatingBar Output

Getting Started

Android RatingBar can be defined 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.

Different Attributes of Android RatingBar 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 –

Example of Android RatingBar Using Kotlin

At first, we will create an android application. Then, we will use ratingBar widget in this application.

1. Creating New Project in Kotlin

Follow steps below to create new project. Please ignore the steps if you have already created the project.

Since we have a project now, we will modify xml and other file to use ratingBar using kotlin file in the application.

2. Modify values folder

No values folders have been modified. So, we are not going to mention them here.

3. Use RatingBar Widget in xml file

Open src/main/res/layout/activity_main.xml file and 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">

	<RatingBar
		android:id="@+id/ratingBar"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:stepSize="0.5"
		android:theme="@style/RatingBar"/>

	<Button
		android:id="@+id/button"
		android:layout_width="wrap_content"
		android:layout_height="wrap_content"
		android:text="Submit"/>

</LinearLayout>

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.

4. Access Android RatingBar Using Kotlin file

Open src/main/java/com.tutorialwing.ratingbar/MainActivity.kt file and add below code into it.

package com.tutorialwing.ratingbar

import android.os.Bundle
import android.support.v7.app.AppCompatActivity
import android.widget.Button
import android.widget.RatingBar
import android.widget.Toast

class MainActivity : AppCompatActivity() {

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

        val ratingBar = findViewById<RatingBar>(R.id.ratingBar)
        if (ratingBar != null) {
            val button = findViewById<Button>(R.id.button)
            button?.setOnClickListener {
                val msg = 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.

Since AndroidManifest.xml file is very important in the application, we are also going to see the content inside this file.

AndroidManifest.xml file

Code inside main/AndroidManifest.xml file is as below.

<?xml version="1.0" encoding="utf-8"?>
<manifest package="com.tutorialwing.ratingbar"
		  xmlns:android="http://schemas.android.com/apk/res/android">

	<application
		android:allowBackup="true"
		android:icon="@mipmap/ic_launcher"
		android:label="@string/app_name"
		android:roundIcon="@mipmap/ic_launcher_round"
		android:supportsRtl="true"
		android:theme="@style/AppTheme">
		<activity android:name=".MainActivity">
			<intent-filter>
				<action android:name="android.intent.action.MAIN"/>

				<category android:name="android.intent.category.LAUNCHER"/>
			</intent-filter>
		</activity>
	</application>

</manifest>

When we run the program, we will get output as shown above.

That’s end of our tutorial on Android RatingBar using Kotlin.