Develop Reference

Ways to work around the Android workManager 15 minute minimum interval?

The game I am working on is a missile-oriented GPS-based combat game on Android. The app checks every 15 minutes to see if the user is under attack by any other players, and if so, sends them a notification that they are under attack. Currently, because of the minimum 15 minute interval, the app sends these notifications either too late or not at all. What I need to do is alter this so that somehow, some way, the app checks the "under attack" status of the user more often than 15 minutes. Every minute or every 30 seconds would be ideal.
here is the doWork() method which starts the notification check:
{
if(!MainActivity.GetRunning())
{
Utilities.DebugLog(context, "AlertService", "Main activity not running. Firing notification service handler.");
NotificationServiceHandler handler = new NotificationServiceHandler(context);
handler.Start();
}
return Result.SUCCESS;
}

WorkManager is not a suitable tool for what you wish to do. You will need to use a foreground service and your own in-process timing engine (e.g., ScheduledExecutorService). That will not work for very long before Doze mode and other power-saving measures take effect, but hopefully your games are only an hour or so long.

Hej theBiscuit,
instead of using WorkManager, you could set up an AlarmManager to wake up the app and check for attacks.
If you want to do it while the app is running, a CountDownTimer could help for short periods of time.

Detect user change clock time after Force Stop app

I can detect change clock time when app in foreground, background, or kill from Recent App by using android.intent.action.TIME_SET follow here.
However, if I Force Stop app in Setting->Apps I can not receive this broadcast anymore.
Currently, I want to detect user change clock time come back to my app after ForceStop so I do
long deltaTimeBeetweenCurrentTimeAndTimeSinceReboot = System.currentTimeMillis() - SystemClock.elapsedRealtime();
long oldDelta = mSharedPreference.getDeltaTimeBeetweenCurrentTimeAndTimeSinceReboot();
if(deltaTimeBeetweenCurrentTimeAndRebootTime - oldDelta > 5000){
// clock time change
}
Idea is I saved a delta between currently time (System.currentTimeMillis()) and time since reboot (SystemClock.elapsedRealtime()). Every time I open app, I will compare oldDelta and newDelta (except the first time install). It work well in case: User Fore Stop app->Change time->come back to app.
However, there is still have 1 case that is: User Fore Stop app -> Change the clock time -> Reboot device -> Open my app. At this time I can not use the above method to check the clock time have changed because after reboot the SystemClock.elapsedRealtime() will reset. How can I detect clock time have changed in that case?
Any help or suggestion would be great appreciate.

Few months ago I was in pretty the same situation. I didn't find any answer to directly solve the case, so I won't help you with it. But I can give you kind of advice:
Look at it with a different point of view.
What I did in my case, I answered myself to questions:
"Do I really want to know that user has changed the time - because I implicitly inform/present the fact to user?"
OR
"Do I want to know that user has changed the time - because I need it to invoke some actions or calculations in the application background?"
In my case I had NO-YES answers. So, for problematic case of Force-Stop + reboot I assumed that the time could had been changed and I reset my application's time configuration likewise the first app launch.
Let me know if it helps you anyway.

It would be hard to implement without external etalon (backend is the best option). You may save time a user force to stop the app and when the app alive again compare with some predefined delta (time window). If you get a "big" difference consider the user is cheating.
You may also play with timestamps of the filesystem to define some inconsistency.

Android AlarmManager run every day 3 pm

I searched but didn't really find something. Just some examples for running AM every 20 seconds after hit a button etc.
I want that on the first start of my app an AM is started which runs every day at 3 pm and checks some things. It should be possible that the AM is running everyday even if the app doesn't start for 2-3 days.
Can anyone help me?

Step #1: Create a Calendar object that represents 3pm tomorrow. Make sure that it is tomorrow, as if it is after 3pm today, just saying "3pm" will give you a time in the past.
Step #2: Use that with AlarmManager. Use setRepeating() for Android 4.3 and below. For Android 4.4 and above, doing something at a precise time is frowned upon, and so you will probably wind up calling setExact() to get control once, then in that code call setExact() again to schedule the next event.
Step #3: If you want to wake up the device when these events occur, use RTC_WAKEUP for the alarm type, and tie it to either a WakefulBroadcastReceiver or a regular BroadcastReceiver that uses my WakefulIntentService.

Know if uptime timer is reset or Android has been rebooted

I have a independent clock created in my application. The clock runs as a different thread in the activity, starting from a base time set by me. I update the clock using the difference between the uptimemillis when I set the clock, and the current uptimemillis. But the uptimetimer, can be reset by Android, and is ever reset when Android reboot.
I only want to know if the uptime timer is reset, to know if the clock is still reliable.
How?

According to the documentation you can use SystemClock.elapsedRealtime()
elapsedRealtime():
Returns milliseconds since boot, including time spent in sleep.
This value will only be reset when the device is restarted. Listen to the broadcast boot_complete and you will know when that is.
The problem with the updateMillis() is clearly noted in the documentation:
uptimeMillis():
Returns milliseconds since boot, not counting time spent in deep sleep. Note: This value may get reset occasionally (before it would otherwise wrap around).
From how I understand the documentation, by using elapsedRealtime your users cannot manipulate your counter.

Handler.postDelayed not called when mobilephone in standby mode

I'm trying to write a simple app that should mute my mobile phone for a given time. It's my first Android app, but after many hours of reading I think it is nearly completed. But it still has one problem that I can not fix.
I'm using a activity to display the GUI. It has Buttons to set the start and end time, and everything else needed. When the user has entered all the parameters, they are passed to a service. This service uses a handler object, to register 2 callbacks (with Handler.postDelayed). One for start Mute and one for End Mute (in SetMuteIntervall).
The first tests seemed to work, but if I try to mute it for like 30 minutes, it never unmutes. I think it has something to do with the fact, that the mobilephone is or was in standby mode. I also tried to use Handler.postAt() but that didn't work either (and time relative to uptime was somewhat confusing).
So, what should I do to guarantee, that my callbacks are called, regardless whether the phone is in standby or not?
Here's the source of my program:
http://pastebin.com/XAgCeAq9
http://pastebin.com/33nepFV5

Try to use AlarmManager for planning some actions in future. AlarmManager is not standby-mode-dependend and will fire even if device is sleeping.
Your thread are actually stopped then the phone is in stand by mode. If you still want to use thread you can use WakeLock to prevent CPU from going to stand by mode (but still to switch screen off) but this is not the best way in your case.