How to communicate between Activity and Service in Android using Kotlin?

This example demonstrates how to communicate between Activity and Service in Android using 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:tools="http://schemas.android.com/tools"
   android:id="@+id/relativeLayout"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   tools:context=".MainActivity">
   <TextView
      android:id="@+id/text2"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_marginTop="70dp"
      android:background="#008080"
      android:padding="5dp"
      android:text="TutorialsPoint"
      android:textColor="#fff"
      android:textSize="24sp"
      android:textStyle="bold" />
   <Button
      android:id="@+id/buttonStart"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_below="@+id/text2"
      android:layout_centerInParent="true"
      android:layout_marginTop="74dp"
      android:text="Start Service" />
   <Button
      android:id="@+id/buttonStop"
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:layout_centerHorizontal="true"
      android:layout_centerVertical="true"
      android:text="Stop Service" />
</RelativeLayout>

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

import android.app.Service
import android.content.Intent
import android.media.MediaPlayer
import android.os.Bundle
import android.os.IBinder
import android.view.View
import android.widget.Button
import android.widget.Toast
import androidx.annotation.Nullable
import androidx.appcompat.app.AppCompatActivity
class MainActivity : AppCompatActivity(), View.OnClickListener {
   private lateinit var buttonStart: Button
   private lateinit var buttonStop: Button
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState)
      setContentView(R.layout.activity_main)
      title = "KotlinApp"
      buttonStart = findViewById(R.id.buttonStart)
      buttonStop = findViewById(R.id.buttonStop)
      buttonStart.setOnClickListener(this)
      buttonStop.setOnClickListener(this)
   }
   override fun onClick(src: View?) {
      when (src?.id) {
         R.id.buttonStart -> startService(Intent(this, MyService::class.java))
         R.id.buttonStop -> stopService(Intent(this, MyService::class.java))
      }
   }
   class MyService : Service() {
      private lateinit var myPlayer: MediaPlayer
      @Nullable
      override fun onBind(intent: Intent?): IBinder? {
         return null
      }
      override fun onCreate() {
         Toast.makeText(this, "Service Created",
         Toast.LENGTH_LONG).show()
         myPlayer = MediaPlayer.create(this, R.raw.song)
         myPlayer.isLooping = false
      }
      override fun onStart(intent: Intent?, startId: Int) {
         Toast.makeText(this, "Service Started",
         Toast.LENGTH_LONG).show()
         myPlayer.start()
      }
      override fun onDestroy() {
         Toast.makeText(this, "Service Stopped",
         Toast.LENGTH_LONG).show()
         myPlayer.stop()
      }
   }
}

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="com.example.q11">
   <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>
      <service android:name=".MainActivity$MyService" />
   </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.