Java Android Scheduling: Work Manager and Alarm Manager
WorkManager:
- Constraints: You can specify conditions like "only run when charging" or "only on Wi-Fi".
- Persistence: Tasks survive device reboots and app crashes.
- Backward Compatibility: It automatically chooses the best underlying API (JobScheduler, AlarmManager, etc.) based on the device's API level.
- Limitation: It does not guarantee exact timing. The system may delay execution to optimize battery life.
AlarmManager
- Precision: Can wake the device from Doze mode to trigger a notification exactly when scheduled.
- Lifecycle Independent: Operates outside your app's lifecycle once set.
- It is resource-intensive because it wakes the device.
- It does not support execution constraints (like network requirements).
- For long-running tasks triggered by an alarm, Google recommends handing off the work to WorkManager from the alarm's BroadcastReceiver.
| Feature | WorkManager | AlarmManager |
| Timing | Deferrable (inexact) | Precise (exact) |
| Guaranteed? | Yes, even after reboot | Not inherently (must reset on reboot) |
| Constraints | Battery, Network, Storage | None (time-only) |
| Power Efficiency | High (optimized by OS) | Low (wakes device) |
| Minimum Interval | 15 minutes for periodic work | None (can be immediate) |
| Supported Version | Known stable on Android 13+ | All |
