An Android Service, is an application component that can perform long-running operations in the background, and it doesn’t provide a user interface.
A few example uses for a service could be:
- Network transactions
- Play music
- Perform file I/O operations
- Interact with content providers
- Background operations
I’ve recently implemented a service in one of my applications to start a sound triggered by a BroadcastReceiver when an alarm expires and here is how I implemented it with Kotlin.
AlarmService.kt
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| package com.isscroberto.powernap.util | |
| import android.app.Service | |
| import android.content.Context | |
| import android.content.Intent | |
| import android.media.Ringtone | |
| import android.media.RingtoneManager | |
| import android.os.IBinder | |
| class AlarmService : Service() { | |
| private lateinit var ringtone: Ringtone | |
| override fun onBind(p0: Intent?): IBinder? { | |
| return null | |
| } | |
| override fun onStartCommand(intent: Intent?, flags: Int, startId: Int): Int { | |
| playAlarm() | |
| return super.onStartCommand(intent, flags, startId) | |
| } | |
| override fun onDestroy() { | |
| super.onDestroy() | |
| ringtone.stop() | |
| } | |
| fun playAlarm() { | |
| val notification = RingtoneManager.getDefaultUri(RingtoneManager.TYPE_ALARM) | |
| ringtone = RingtoneManager.getRingtone(this, notification) | |
| if(!ringtone.isPlaying()) { | |
| ringtone.play() | |
| } | |
| } | |
| } |
Then, this is how it’s started from the BroadcastReceiver.
TimerExpiredReceiver.kt
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| package com.isscroberto.powernap | |
| import android.content.BroadcastReceiver | |
| import android.content.Context | |
| import android.content.Intent | |
| import com.isscroberto.powernap.data.NapState | |
| import com.isscroberto.powernap.util.NotificationUtil | |
| import com.isscroberto.powernap.util.PrefUtil | |
| import com.isscroberto.powernap.util.AlarmService | |
| class TimerExpiredReceiver : BroadcastReceiver() { | |
| override fun onReceive(context: Context, intent: Intent) { | |
| // Show notification of expiration. | |
| NotificationUtil.showTimerExpired(context) | |
| // Save status in preferences. | |
| PrefUtil.setTimerState(NapState.Finished, context) | |
| PrefUtil.setAlarmSetTime(0, context) | |
| // Play alarm sound. | |
| context.startService(Intent(context, AlarmService::class.java)) | |
| } | |
| } |
Finally don’t forget to add your reference to your app’s manifest file.
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| <service android:name=".util.AlarmService"/> |
By using this service I’m able to stop it from anywhere within the application and stop the alarm sound when the user interacts with my app by calling stopService().
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| // Stop alarm. | |
| context!!.stopService(Intent(context!!, AlarmService::class.java)) |
I implemented this functionality in PowerNap, an app that will help you take efficient naps by controlling the time you sleep. You can find the source code in GitHub.