how to keep an Intent service running

Question

I have two examples of Intentservice. One is the Download example in the commonsware book. the other is at http://www.vogella.com/articles/AndroidServices/article.html#servicecommunication_handler. Both of these examples show the service executing a finite task and they both apparently destroy themselves by running to the end of the scope of the onHandleIntent event.

The service I am writing has to have events and listen for things. One is a LocationListener listening for GPS movement. Another makes Posts to a REST service and listens for replys. I want it to run until a time has elapsed or until it was told to quit by the activity that started it.

How do I keep it running? Where, for instance, do I put my implementation of LocationListener? Thanks, Gary

Myrlmyrle

even i need an answer to the same question, in my case i am starting a flashlight from widget , but its getting killed. – Harwilll

Answer 1

How do I keep it running?

You don't. IntentService is designed to do a piece of work (or perhaps a few off a queue, if commands happen to come in rapidly), then shut down.

The service I am writing has to have events and listen for things.

Then you should not be using an IntentService. Use a regular Service, with your own background thread(s) as needed.

Littell

Can someone qualify this answer? IntentService is a subclass of Service, so why should only the latter be used (in a new thread) for long-running / ongoing operations?? – Trstram

@ban-geoengineering: As I wrote, IntentService was designed around transactional operations, where the work is done fairly quickly and the service should then shut down. If you want something that will run longer than that, create your own Service with your own controls for when the Service stops itself (or is stopped by a client via stopService()). – Littell

I understand what you've said, but I'd like to know where you have got this information from so I can verify for myself that this is indeed the case. – Trstram

@ban-geoengineering: Discussions with Google engineers, mostly. – Littell

Is it not documented anywhere? – Trstram

@ban-geoengineering: Developer intentions when designing and implementing a class are not usually documented. If you don't like the advice, don't follow it. – Littell

This is just not true. You can do anything inside IntentService which you would do with a regular service. All it does is it provides message queue to the thread executing HandleIntent. You can still put service in foreground all the same. – Piperine

@SergeyA: "All it does is it provides message queue to the thread executing HandleIntent." -- and immediately shuts down once the work is completed. That is why computer programmers use it for a transactional bit of work. You are certainly welcome to use startForeground() for that transaction. But the question is about LocationListener; that is intrinsically asynchronous and therefore unsuitable for IntentService. – Littell

@CommonsWare, you just never return from HandleIntent. – Piperine

@SergeyA: I do not recommend that solution. Never indefinitely tie up a resource (e.g., a thread) that you did not create yourself. – Littell

@CommonsWare, as good solution is any. I see no problem with it. – Piperine

The documentation now says All requests... may take as long as necessary (and will not block the application's main loop)...: developer.android.com/reference/android/app/IntentService.html – Trstram

@ban-geoengineering: "as long as necessary" does not mean "indefinitely". – Littell

I've used the foreground intent service approach (as mentioned by Luis: https://mcmap.net/q/590993/-how-to-keep-an-intent-service-running ) and my intent service usually runs for hours/days/weeks. – Trstram

@Littell I'm not sure about that. From my experience, "as long as necessary" is more towards the "indefinitely" end of the spectrum that the "just a few seconds" end. – Trstram

@Littell your comments like from holy book man. is that still true that which is the part of "You don't..." after 5 years in 2017. if YES, are you prefer to use normal 'Service'? – Offering

@mehmet: "is that still true..." -- yes. "are you prefer to use normal 'Service'?" -- that depends. In general, having long-running background started services of any type is not a good idea, which is why on Android 8.0+, they only run for a minute. A foreground service (startForeground()) could run for a longer period of time. Frequently, there is some other solution to the problem (e.g., JobScheduler for periodic work). – Littell

Answer 2

You can achieve this in either of two ways,

• AlarmManager
• TimerTask

AlarmManager is android's in-buite class that allows you to execute certain action on particular time peroid.

TimerTask does same thing as AlarmManager, you can repeat certain action of your code again and again.

However AlarmManager is ligher in the execution so i suggest you to go with AlarmManager class.

Create an AlarmManager that fetches the GPS Co-ordinates and post them to server on regular interval basis.

Have a look at to this AlarmManager Example.

Jacks

Neither of your suggestions will prevent the IntentService from being destroyed. You cannot keep it alive, without waiting in the handleIntent method. – Smithy

@bluewhile I think Lucifer is basically providing an alternative to using IntentService for this particular task. – Discourteous

Answer 3

To keep a service running, your service need to return START_STICKY in the service method onStartCommand().

With this, the service will be running even if you exit form your activity.

Note: The Android still kills services after some time (30 mintus to 1 hour) if they are not foreground services. Use startForeground(notification) to make it foreground.

good luck

Guidry

This doesn't explain how to run IntenService indefinitely. – Sympetalous