How to use Alarm Manager in Android?

This example demonstrates how to use AlarmManager 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"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
   android:padding="8dp" tools:context=".MainActivity">
<LinearLayout android:id="@+id/linearLayout"
   android:layout_width="match_parent"
   android:layout_height="wrap_content"
   android:layout_centerVertical="true"
   android:orientation="vertical">
<TimePicker android:id="@+id/timePicker"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content" />
<Button android:layout_gravity="center"
   android:id="@+id/buttonAlarm"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:text="Set Alarm" />
   </LinearLayout>
</RelativeLayout>

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

import android.app.AlarmManager
import android.app.PendingIntent
import android.content.BroadcastReceiver
import android.content.Context
import android.content.Intent
import android.os.Build
import android.os.Bundle
import android.util.Log
import android.widget.Button
import android.widget.TimePicker
import android.widget.Toast
import androidx.appcompat.app.AppCompatActivity
import java.util.*
class MainActivity : AppCompatActivity() {
   lateinit var btnSetAlarm: Button lateinit
   var timePicker: TimePicker
   override fun onCreate(savedInstanceState: Bundle?) {
      super.onCreate(savedInstanceState) setContentView(R.layout.activity_main)
      title = "KotlinApp"
      timePicker = findViewById(R.id.timePicker)
      btnSetAlarm = findViewById(R.id.buttonAlarm)
      btnSetAlarm.setOnClickListener {
         val calendar: Calendar = Calendar.getInstance()
         if (Build.VERSION.SDK_INT >= 23) {
            calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH),          calendar.get(Calendar.DAY_OF_MONTH), timePicker.hour, timePicker.minute, 0)
         }
         else {
            calendar.set(calendar.get(Calendar.YEAR), calendar.get(Calendar.MONTH), calendar.get(Calendar.DAY_OF_MONTH), timePicker.currentHour, timePicker.currentMinute, 0)
         }
         setAlarm(calendar.timeInMillis)
      }
   }
   private fun setAlarm(timeInMillis: Long) {
      val alarmManager = getSystemService(Context.ALARM_SERVICE) as AlarmManager
      val intent = Intent(this, MyAlarm::class.java)
      val pendingIntent = PendingIntent.getBroadcast(this, 0, intent, 0)       alarmManager.setRepeating(AlarmManager.RTC, timeInMillis, AlarmManager.INTERVAL_DAY, pendingIntent) Toast.makeText(this, "Alarm is set", Toast.LENGTH_SHORT).show()
      }
      private class MyAlarm : BroadcastReceiver() {
         override fun onReceive(context: Context, intent: Intent) {
            Log.d("Alarm Bell", "Alarm just fired")
         }
    }
}

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>
   </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.