How to start service using Alarm Manager in android?

This example demonstrates how do I start a service using alarm manager in android.
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"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   android:id="@+id/activity_main"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:padding="16sp"
   android:orientation="vertical"
   android:gravity="center_horizontal">
   <Button
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:id="@+id/btnStartService"
      android:text="Start Service Alarm"
      android:layout_marginTop="30dp"/>
   <Button
      android:id="@+id/btnStopService"
      android:layout_width="match_parent"
      android:layout_height="wrap_content"
      android:layout_marginTop="10dp"
      android:text="Cancel Service"/>
</LinearLayout>
Step 3 − Add the following code to src/MainActivity.java
package app.com.sample;
import android.app.AlarmManager;
import android.app.PendingIntent;
import android.content.Intent;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.Toast;
import java.util.Calendar;
public class MainActivity extends AppCompatActivity {
   Button btnStart, btnStop;
   PendingIntent pendingIntent;
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
      btnStart = findViewById(R.id.btnStartService);
      btnStop = findViewById(R.id.btnStopService);
      btnStart.setOnClickListener(new View.OnClickListener() {
      @Override
      public void onClick(View v) {
         Intent myIntent = new Intent(MainActivity.this, MyAlarmService.class);
         pendingIntent = PendingIntent.getService(MainActivity.this, 0, myIntent, 0);
         AlarmManager alarmManager = (AlarmManager)getSystemService(ALARM_SERVICE);
         Calendar calendar = Calendar.getInstance();
         calendar.setTimeInMillis(System.currentTimeMillis());
         calendar.add(Calendar.SECOND, 3);
         assert alarmManager != null;
         alarmManager.set(AlarmManager.RTC_WAKEUP, calendar.getTimeInMillis(), pendingIntent);
         Toast.makeText(MainActivity.this, "Starting Service Alarm", Toast.LENGTH_LONG).show();
      }});
      btnStop.setOnClickListener(new View.OnClickListener() {
         @Override
         public void onClick(View v) {
            AlarmManager alarmManager = (AlarmManager)getSystemService(ALARM_SERVICE);
            assert alarmManager != null;
            alarmManager.cancel(pendingIntent);
            Toast.makeText(MainActivity.this, "Service Cancelled", Toast.LENGTH_LONG).show();
         }
      });
   }
}
Step 4 – Create a java class (MyAlarmService.java) and add the following code?
import android.app.Service;
import android.content.Intent;
import android.os.IBinder;
import android.support.annotation.Nullable;
import android.widget.Toast;
public class MyAlarmService extends Service {
   @Override
   public void onCreate() {
      Toast.makeText(this, "MyAlarmService.onCreate()", Toast.LENGTH_LONG).show();
   }
   @Nullable
   @Override
   public IBinder onBind(Intent intent) {
      Toast.makeText(this, "MyAlarmService.onBind()", Toast.LENGTH_LONG).show();
      return null;
   }
   @Override
   public void onDestroy() {
      super.onDestroy();
      Toast.makeText(this, "MyAlarmService.onDestroy()", Toast.LENGTH_LONG).show();
   }
   @Override
   public void onStart(Intent intent, int startId) {
      super.onStart(intent, startId);
      Toast.makeText(this, "MyAlarmService.onStart()", Toast.LENGTH_LONG).show();
   }
   @Override
   public boolean onUnbind(Intent intent) {
      Toast.makeText(this, "MyAlarmService.onUnbind()", Toast.LENGTH_LONG).show();
      return super.onUnbind(intent);
   }
}
Step 5 − 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.sample">
   <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=".MyAlarmService" />
   </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 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.