How to use CheckBox in Android Kotlin?

This example demonstrates how to use CheckBox in Android Kotlin.

Step 1 − Create a new project in Android Studio, go to File ⇒New Project and fill all required details to create a new project.

Step 2 − Add the following code to res/layout/activity_main.xml.

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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"
   android:padding="16dp"
   tools:context="MainActivity">
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="50dp"
      android:text="Tutorials Point"
      android:textAlignment="center"
      android:textColor="@android:color/holo_green_dark"
      android:textSize="32sp"
      android:textStyle="bold" />
   <TextView
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_above="@id/checkBox1"
      android:layout_marginBottom="30dp"
      android:text="Select your products!"
      android:textAlignment="center"
      android:textColor="@android:color/background_dark"
      android:textSize="24sp"
      android:textStyle="bold|italic" />
   <CheckBox
      android:id="@+id/checkBox1"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerInParent="true"
      android:text="Pizza" />
   <CheckBox
      android:id="@+id/checkBox2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@id/checkBox1"
      android:layout_centerInParent="true"
      android:layout_marginTop="10dp"
      android:text="Coffee" />
   <CheckBox
      android:id="@+id/checkBox3"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@id/checkBox2"
      android:layout_centerInParent="true"
      android:layout_marginTop="10dp"
      android:text="Burger" />
   <Button
      android:id="@+id/button"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_below="@id/checkBox3"
      android:layout_marginTop="10dp"
      android:text="Complete purchase" />
</RelativeLayout>

Step 3 − Add the following code to src/MainActivity.kt

import android.os.Bundle
import android.widget.Button
import android.widget.CheckBox
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import java.lang.StringBuilder
class MainActivity : AppCompatActivity() {
   lateinit var pizza: CheckBox
   lateinit var coffee: CheckBox
   lateinit var burger: CheckBox
   lateinit var button: Button
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      pizza = findViewById(R.id.checkBox1)
      coffee = findViewById(R.id.checkBox2)
      burger = findViewById(R.id.checkBox3)
      button = findViewById(R.id.button)
      button.setOnClickListener {
         var totalAmount: Int = 0
         val result = StringBuilder()
         result.append("Selected Items")
         if (pizza.isChecked) {
            result.append("
Pizza 100Rs")
            totalAmount += 100
         }
         if (coffee.isChecked) {
            result.append("
Coffee 50Rs")
            totalAmount += 50
         }
         if (burger.isChecked) {
            result.append("
Burger 120Rs")
            totalAmount += 120
         }
         result.append("
Total: " + totalAmount + "Rs")
         Toast.makeText(applicationContext, result.toString(), Toast.LENGTH_SHORT).show()
      }
   }
}

Step 4 − Add the following code to androidManifest.xml

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

Let's try to run your application. I assume you have connected your actual Android Mobile device with your computer. To run the app from android studio, open one of your project's activity files and click the Run icon from the toolbar. Select your mobile device as an option and then check your mobile device which will display your default screen −

Click here to download the project code.