I am a beginner. I want to develop an application which can generate location based notifications. In android developer website I found in order to maintain a balance between battery life and data exchange one should consider
frequency of new updates
window in which you listen for location updates.
I know frequency can be controlled by calling requestLocationUpdates(). My question is how can I control the window in which I listen for updates ? Does it mean that once I acquire the location update from onLocationChanged() method of LocationListener class, I should stop listening for updates using removeUpdates() ??
Thanks
GPS device only start working (and consuming power) when you register for requestLocationUpdates().
Teoretically the GPS can switch off between updates if they are not very frequent. Let's say for example that you have requested updates every 5 minutes, then the GPS can switch off for 4 minutes and 30 secounds aprox. and switch on in time to acquire the next location. If you set the new locations requests for every 5 secounds, GPS will not switch off between updates.
I have one application that keeps GPS awake full time, recording the locations in a database. This application can also show a map and draw the track recorded. My experience is that the power used to draw the map with track changing in real time is much higher then the power used by the GPS.
good luck
I think you should stop listenting for updates only when you don't need anymore new locations. If you need only one new location, stop listenting right away is the best approach. For getting more locations(as the user moves) it's recommended to start listen for location updates in onResume and stop listenting in onPause. That means your onLocationChanged will be called only when your activity is in front of all others (is visible).
In conclusion, the activity that manages the window you need should have these calls as specified above.
Related
I need to keep rough track of a users position, but not really in real time. It's sufficient to handle the location updates when the app is started. However, I still need to know where the user was when the app wasn't running.
Is there a way to get the location history in an app?
I don't really want to have a service just polling last known location all the time since that would be a waste of battery power.
However, I still need to know where the user was when the app wasn't running.
That is not possible.
I don't really want to have a service just polling last known location all the time since that would be a waste of battery power.
Then eliminate your requirement for location history. You only get the locations that you request.
Rough Track can mean you get location of the user (lastKnown or Fresh) after every n-hours. Doing this will not require a service, simply a recurring alarm and receiver will do. In the onReceive method of receiver, you can manage a stack of locations in your app.
You will have to reset the alarm though when the device re-boots. I guess this is an add-on, rest should work fine.
you can not get current location without running your app...
the second way is to make background service ..wich you don't wan't to make...
The other way is to run background service using Alarammanager whenever you want after getting location you can stop the service...like you can make call every hour or 2 times per day...
I have registered a location listener, which will receive location updates using NETWORK_PROVIDER. The listener receives location updates if the activity is in foreground. If I leave the app, after some time it stops receiving location updates. Which is a bit weird... isn't it supposed to receive location update even if none of the activity is on the stack? The listener starts receiving location updates again if I go back to my app.
Or am I doing something wrong? What programming model is suggested to receive location updates even if none of my activity is not active (neither on foreground, nor on stack)?
There are some other way to receive location updates (using pending intent), but those do not trigger if I do not turn on GPS.
The activity in the background will be eventually destroyed, you don't have any guarantee that once stopped it will continue receiving location updates. Activities in Android are not supposed to be used like this.
You can use a service with a wake lock as suggested, but keeping the device awake will quickly drain your battery.
I recommend you this talk by Reto Meier (IO 2011), where he talks about different strategies to have a fresh location. Here is the code.
I'm looking for the best way to continually monitor the location of an Android device, while using the lowest amount of battery power. My project is basically a phone tracking service, with phone call / sms logging, and location tracking. There is a web interface, which would eventually allow a person to change settings (such as location update interval, so if it was stolen they could track it more effectively), but as standard it should update the location every 30-60 minutes.
I was thinking of using a Service, but would it be better to start a service, request location updates, and then finish? Or some other method?
Cheers
but would it be better to start a service, request location updates, and then finish?
Yes, simply so you do not need to keep a service around all the time. However, it's a bit more complicated than that:
you might never get a fix (e.g., the phone is underground and cannot get GPS signals)
you need to keep the service around until you get a fix or until some timeout occurs
you have to worry about the device falling asleep while all this is going on
I have a LocationPoller component that handles most of that.
I have an android application. Based on the current geo location of user, I want to fetch some remote data in background and store it. My implementation is:
At specific interval a alarm fires up my service. Service uses an anonymous class to query current location and registers a locationListener callback. On call of onLocationChanged() I initiate the remote data fetch from server.
However once my service is done registering the location listener using anonymos class, it returns as expected; as it doesn't wait for callback to happen before finishing. Since callback takes some time and makes a call when service has already returned, it throws an error saying:
java.lang.RuntimeException: Handler{43e82510} sending message to a Handler on a dead thread
Which is quite understandable. One quick workaround for me now is that I can use getLastKnownLocation from locationManager as that doesn't respond back by callback; but what if I do want the latest location right now, in a service and not activity? How can I wait for callback to happen and stop my service from returning.
Also, at what point does lastKnownlocation gets updated? Everytime GPS registers a new location; does it update it? What I want to know is that if it's not latest can it still be closed to latest? As I didn't see an option in android emulator to configure the time period between subsequent updates.
Any help is much appreciated.
Cheers
but what if I do want the latest location right now, in a service and not activity?
Sorry, but that is not possible, in either a service or an activity. For example, if the GPS radio is off, and you are requesting location data from GPS, it will take tens of seconds just to get a fix, and that's if you are lucky. It might not get a fix at all.
How can I wait for callback to happen and stop my service from returning.
You don't. You do what you said you would do:
use getLastKnownLocation from locationManager as that doesn't respond back by callback
So, have your Service (which is hopefully an IntentService) check to see if getLastKnownLocation() happens to have a value. If it does, use it. Otherwise, registerLocationUpdates() using a PendingIntent that will pass control back to your IntentService. When you get that Intent, use the location and unregister for updates (assuming the alarm period is nice and long, like, say, once an hour).
Things get tricky if your alarm is a _WAKEUP alarm. You will then need to hold a WakeLock, so the device does not fall back asleep while you are trying to get a GPS fix. However, you need to release that WakeLock sometime, and if we cannot get a GPS fix...ummm...well, that's the tricky part. Trying to figure out a nice clean way of handling this, and implementing it as a reusable component (e.g., LocationAlarmService), is one of 18,000 items on my to-do list.
Also, at what point does lastKnownlocation gets updated? Everytime GPS registers a new location; does it > update it?
AFAIK, yes.
I would like to write an app on Android to upload my GPS location to an external website once every ~5 minutes. This needs to have as minimal an impact on battery life as possible, but it also needs to work without any user interaction. (Background: I'm competing in an Ironman triathlon which will take me about 14 hours to complete, and want to broadcast my location in near-real-time but without having to worry about fiddling with my phone.)
So my initial thought is to write a Service which uses LocationManager.requestLocationUpdates() with a minTime of 5 minutes, but will this actually wake the device up every 5 minutes for my service to do its job?
It sounds like I would also need to use AlarmManager.setInexactRepeating() to make sure my service is awake while it completes its task but how does that play with requestLocationUpdates()? Should I instead set minTime=0 on requestLocationUpdates() but then go back to sleep as soon as the next update is obtained?
Any general guidance on how to design this is greatly appreciated. I'm a competent Java programmer & will be using Google Maps on the server to plot my location, but am pretty new to Android development so I'm basically looking for a high-level plan on how to architect the client app.
Your service must be alive all the time you want to receive updates.
http://developer.android.com/reference/android/location/LocationManager.html#requestLocationUpdates%28java.lang.String,%20long,%20float,%20android.location.LocationListener%29
You can tell how often you want to be informed of location change with minTime parameter. It does not however decrease battery consumption. GPS is enabled unless you use removeUpdates method no matter how often you want to receive updates.
You can use another approache:enable GPS using method above, read one value, use removeUpdates method, wait 5 minutes and all over again. Delay between enabling and retreiving a location can be between few seconds to few minutes.