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Enough of this stopping services stuff.

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Let's get back to the par with
the invincible service refuses today.

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But first a quick recap.

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The return value of onStarCommand
represents what will happen to a service

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if its process is killed after
returning from onStarCommand,

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but before being stopped.

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Put more simply,

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it's what will happen if your service
is killed without finishing its work.

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Earlier I mentioned that there
are three constants we can return from

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onStarCommand.

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Those constants are START_STICKY,
START_NOT_STICKY, and

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START_REDELIVER_INTENT.

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There's actually a fourth value
START_STICKY_COMPATIBILITY.

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But it's not important to learn about,
so we've just got START_STICKY,

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START_NOT_STICKY, and
START_REDELIVER_INTENT.

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Let's kick things off with START_STICKY.

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Returning Service.START_STICKY and

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onStartCommand tells Android to restart
our service using a null intent.

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This is useful for things you might
want to leave running for a long time.

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Like a music player or
an app to track where you went on a run.

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Once these things are started, it's up
to the user to decide when to stop them.

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If I'm out running and Android kills
my run tracking app, I'm going to be

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pretty unhappy if it doesn't come back and
track the rest of my run.

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S is just what you think it would be.

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If we return Service.START_NOT_STICKY
from onStartCommand,

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then our service won't be restarted.

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An example of this would be a service
that checks for new emails in your inbox.

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And let say this service is
started every five minutes.

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So every five minutes,

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this service will run and
update your inbox with any new messages.

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But if Android is so
burdened that it kills your app,

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it's probably not the best idea to throw
rescheduling this service into the mix.

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After all, it'll be started
again in five minutes anyway.

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Last, but not least,
is START_REDELIVER_INTENT.

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If we return
Service.START_REDELIVER_INTENT

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from onStartCommand, our service will be
restarted using the last delivered intent.

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In fact, for every intent,

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if the associated start ID hasn't
been included in a call to stop self

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then our service's onStartCommand
method will be called with the intent.

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Here's an example.

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Let's say we've downloaded the first two
songs and then our process gets killed.

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Since we've only downloaded
two songs we haven't yet

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called stopSelf for songs 3, 4 or 5.

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So the three intense associated with
these songs will be redelivered to

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our service when it's restarted.

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And there we go.

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Those are the three things we can have
happen when our process is killed

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while our service is still working.

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We can restart the service with
a null intent, START_STICKY,

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not restart the service, START_NOT_STICKY,
or restart the service and

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redeliver all unfinished intents,
START_REDELIVER_INTENT.