How To Properly Update A Widget In Android 8.0 - Oreo - API 26

Question

Let\'s say I have a widget for an app that has targetSDKVersion set to 26. This widget takes between 100ms and 10s to update. Most of the time under 1s. Before Android O, if

Answer 1

You don't indicate what the update trigger mechanism is. You seem concerned about latency ("Your widget may or may not get updated for a while"), so I am going to assume that your concern is tied to user interaction with the app widget, such as tapping a button.

Use JobScheduler to schedule a job as quickly as possible. Your widget may or may not get updated for a while.

This is a variation on "use JobIntentService", which AFAIK is the recommended solution for this sort of scenario.

Other options include:

• Use getForegroundService() with PendingIntent. With this, you effectively "pinky swear" that your service will call startForeground() within the ANR timeframe. If the work takes longer than a few seconds, call startForeground() to ensure that Android doesn't get cranky. This should minimize the number of time the foreground notification appears. And, if the user tapped a button and you are still busy doing work a few seconds later, you probably want to show a notification or otherwise do something to let the user know that what they asked for is still in progress.

• Use goAsync() on BroadcastReceiver, to do work in the context of the receiver while not tying up the main application thread. I haven't tried this with Android 8.0+, so YMMV.

Answer 2

You can use WorkManager to update a widget. Uses WorkManager on devices with API 14+. You need to override fun onReceive(context: Context?, intent: Intent?) like this:

val ACTION_AUTO_UPDATE : String = "AUTO_UPDATE";

override fun onReceive(context: Context?, intent: Intent?) {
    super.onReceive(context, intent)
    if(intent?.action.equals(ACTION_AUTO_UPDATE))
    {
        val appWidgetManager = AppWidgetManager.getInstance(context)
        val thisAppWidgetComponentName = ComponentName(context!!.getPackageName(), javaClass.name)
        val appWidgetIds = appWidgetManager.getAppWidgetIds(thisAppWidgetComponentName)
        for (appWidgetId in appWidgetIds) {
            // update widget
        }
    }
}

And you should create PeriodicWorkRequest. You have to use for repeating work. Periodic work has a minimum interval of 15 minutes. We enqueue the periodicWork when widget is enabled:

override fun onEnabled(context: Context) {
    val periodicWorkRequest = PeriodicWorkRequest.Builder(YourWorker::class.java, 15, TimeUnit.MINUTES).build()
    WorkManager.getInstance(context).enqueueUniquePeriodicWork("YourWorker", ExistingPeriodicWorkPolicy.REPLACE,periodicWorkRequest)
}

And cancel it when widget is disabled:

override fun onDisabled(context: Context) {
    WorkManager.getInstance(context).cancelAllWork()
}

Finally we create worker class:

class YourWorker(ctx: Context, params: WorkerParameters) : Worker(ctx, params) {
var context : Context? = null

init {
    context = ctx
}

override fun doWork(): Result {
    val alarmIntent = Intent(context, YourWidget::class.java)
    alarmIntent.action = YourWidget().ACTION_AUTO_UPDATE
    context?.sendBroadcast(alarmIntent)
    return Result.success()
}

If you want to use WorkerManager you add to build.gradle implementation 'androidx.work:work-runtime:2.3.1'

You can find the sample here.