Hi,
It is Upon to you to decide if you want to do startService() or
bindService()
The meaning of startService is: wake up the service (create it if
doesn't exist) and give it this command.
The service should know what's doing and, if the command is already
running should just discard the new request (or whatever logic fit your
app).
BindService say: give me a binder object to the service so that I can
ask it directly for information.
Usually you send command with startService() and then forgot you asked
for them.
If you want to know the state of a Service instead you bind to it.
A good practice I use when I have to show the state of some operation
going on in background is binding to a service in the activity
onCreate() and unbinding in onDestroy().
I define my service with a binder interface to let binded activities ask
for informations about the state of the service (how many task are
running, how many are pending, the progress of each one for example) and
when I need (or when the user ask) I start a command with
startService(). I develop the service so that it know what it is doing
(which threads are running and doing what) so I know when to call
stopSelf() when no more threads / operations are running.
I think Google Play app is doing something similar when showing if you
are installing / upgrading an application.
This works very well because even if your activity die, is rotated or
you need to know what's going on from different activities you just have
to bind to it and ask.
Said so if you need to sync data remotely when opening your activity you
should be using SyncAdapters
http://developer.android.com/training/sync-adapters/index.html
Regards,
Daniele Segato
On 08/08/2013 08:02 PM, ashish wrote:
Hi,
suppose an activity start a background service in the oncreate method
and now user switch to other activity and when my app is working in the
background then system kill my activity life-cycle but when i return to
my activity then system call the oncreate method of my application and
then android system again start a new service again even the last one
working in the background..
On Thursday, August 8, 2013 4:53:27 AM UTC-8, Daniele Segato wrote:
On 08/08/2013 01:40 PM, ashish wrote:
> I read about services in Android very carefully, but I didn't
find any
> valid reasons to use it. E.g.
>
> 1.
>
> By default services run in the main thread, which most of the
> applications don't want.
>
> 2.
>
> A service can run on a seperate thread if it spawns it own
thread.
> But if a service runs on a seprate thread, then the method
> |stopService(new Intent(getApplicationContext(),
> MyService.class));| does not stop the running service. Again
this is
> a problem.
>
> If we want to do some background operations, then I think threads
are
> better than services. Am I right?
You've been already told by others that Services should be used to
MANAGE separate thread(s).
The important part is that while an application is used to interact
with
the user a Service has no UI and can run in background.
And with "background" I don't necessary mean off-the-main-thread.
I mean that they can run even if the application (activities) is not
used at the time.
Services have a simpler life cycle in respect to activities and they
are
not influenced or killed by the framework by changes in configurations.
Furthermore the framework will kill activities before starting to kill
services. And if the framework decide to kill your service you can
specify what you want to do with the request you received (drop it, ask
the framework to re-do it, etc...)
Services are a main component of the system and it is good practice to,
for example, use them to update underling data (better if using a
SyncAdapter) and manage remote calls.
regards,
Daniele Segato
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