I have a fairly standard Service which I wish to trigger using an alarm. Here's the initiation section of the service:
class MyService extends Service {
private Context context;
private AlarmManager alarmManager = null;
private final String startReason = "com.stuff.myreason";
private final int REASON_NO_INTENT = 0;
private final int REASON_ALARM = 1;
private final int REASON_X = 2; // and so on.
@Override
void onCreate() {
super.onCreate();
context = getApplicationContext();
alarmManager = (AlarmManager)getSystemService(ALARM_SERVICE);
// do onCreate stuff
}
@Override
int onStartCommand (Intent intent, int flags, int startId) {
int reason = REASON_NO_INTENT;
if (intent != null) {
reason = intent.getExtra(startReason, REASON_NO_INTENT);
}
switch(reason) {
// handle the different reasons we may have been "started"
}
return START_STICKY;
}
}
When I trigger it using context.startService from an activity, it starts absolutely normally. In particular, if it is already running it doesn't (re)start from scratch but simply enters the existing instantiation via onStartCommand()
. This is the expected behaviour. However, when I trigger it using the AlarmManager:
Intent intent = new Intent(context, MyService.class);
intent.putExtra(purposeOfStartCode, REASON_ALARM);
PendingIntent pi = PendingIntent.getService(context, 0, intent, PendingIntent.FLAG_UPDATE_CURRENT);
alarmManager.set(AlarmManager.RTC_WAKEUP, /* A time in the future */, pi);
When the alarm is due it seems to restart the service from scratch: it starts a new instantiation, calls onCreate()
and then onStartCommand()
rather than just calling onStartCommand()
in the already running instantiation.
I have already tried changing the PendingIntent
flag to FLAG_ONE_SHOT
and replacing context
with MyService.this
with no improvement.
I am rather bemused by this - can anyone explain this behaviour and suggest ways to get it to behave as expected?
EDIT - The collection of actions that resulted in a solution are in my answer below.