Manipulating Broadcast Receivers On Demand

The simplest way to monitor device state changes is to create a BroadcastReceiver for each state you're monitoring and register each of them inyour application manifest. Then within each of these receivers you simply reschedule your recurringalarms based on the current device state.

A side-effect of this approach is that your app will wake the device each time any of thesereceivers is triggered—potentially much more frequently than required.

A better approach is to disable or enable the broadcast receivers at runtime. That way you canuse the receivers you declared in the manifest as passive alarms that are triggered by system eventsonly when necessary.

Toggle and Cascade State Change Receivers to Improve Efficiency

---

Use can use the PackageManager to toggle the enabled state on anycomponent defined in the manifest, including whichever broadcast receivers you wish to enable ordisable as shown in the snippet below:

ComponentName receiver = new ComponentName(context, myReceiver.class);PackageManager pm = context.getPackageManager();pm.setComponentEnabledSetting(receiver,        PackageManager.COMPONENT_ENABLED_STATE_ENABLED,        PackageManager.DONT_KILL_APP)

Using this technique, if you determine that connectivity has been lost, you can disable all ofyour receivers except the connectivity-change receiver. Conversely, once you are connected you canstop listening for connectivity changes and simply check to see if you're online immediately beforeperforming an update and rescheduling a recurring update alarm.

You can use the same technique to delay a download that requires higher bandwidth to complete. Simply enable a broadcast receiver that listens for connectivity changes and initiates thedownload only after you are connected to Wi-Fi.