requestLocationUpdates / non-UI-thread / getMainLooper()

[Pent]

Is there anything wrong with specifying the main thread looper to
handle messages about location update like this:

lm.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
0L,
0L,
locListenerGPS,
Looper.getMainLooper()
);

(call is made from a non-UI thread)

Am I going to start getting weird unexplicable errors in other places
due to the looper voodoo ?

Thanks,

Pent

[ADRA]

I could be wrong about this due to inexperience, but due to the nature
of the looper, if you put it on the main looper and the GPS decides to
randomly disappear for seconds then the GUI freezes along with it. I
don't know if that really happen in reality, but I imagine the
possibility could occur. If you want to make sure that the location
updates don't mess up your UI you could always do something like:


class MyLocThread extends Thread
{
public MyLocThread ()
{
setDaemon(true);
setName("LocationThread");
}

public void run()
{
Looper.prepare();
lm.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
0L,
0L,
locListenerGPS,
Looper.getLooper()
);
Looper.loop();
}
}

Post by Pent
Is there anything wrong with specifying the main thread looper to
lm.requestLocationUpdates(
  LocationManager.GPS_PROVIDER,
  0L,
  0L,
  locListenerGPS,
  Looper.getMainLooper()
);
(call is made from a non-UI thread)
Am I going to start getting weird unexplicable errors in other places
due to the looper voodoo ?
Thanks,
Pent

[Kostya Vasilyev]

Being able to specify a Looper in requestLocationUpdates seems to imply that
LocationManager uses Looper/Message mechanism to deliver location updates to
the application.

Using the UI Looper seems safe then, since location update messages would be
delivered to the main thread, decoded into Java callback method calls, and
invoked as usual.

--
Kostya Vasilyev -- http://kmansoft.wordpress.com

29.09.2010 21:13 пПльзПватель "ADRA" <***@gmail.com> МапОсал:

I could be wrong about this due to inexperience, but due to the nature
of the looper, if you put it on the main looper and the GPS decides to
randomly disappear for seconds then the GUI freezes along with it. I
don't know if that really happen in reality, but I imagine the
possibility could occur. If you want to make sure that the location
updates don't mess up your UI you could always do something like:


class MyLocThread extends Thread
{
public MyLocThread ()
{
setDaemon(true);
setName("LocationThread");
}

public void run()
{
Looper.prepare();

lm.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
0L,
0L,
locListenerGPS,
Looper.getLooper()
);
Looper.loop();

}
}

Is there anything wrong with specifyi...

[Kostya Vasilyev]

FYI - ..... and in fact, it does:

http://www.netmite.com/android/mydroid/frameworks/base/location/java/android/location/LocationManager.java

Constructor for ListenerTransport (a helper class that delivers updates
to the application):

if (looper == null) {
mListenerHandler = new Handler() {
@Override
public void handleMessage(Message msg) {
_handleMessage(msg);
}
};
} else {
mListenerHandler = new Handler(looper) {
@Override
public void handleMessage(Message msg) {
_handleMessage(msg);
}
};
}

Implementation of _handleMessage():

switch (msg.what) {
case TYPE_LOCATION_CHANGED:
Location location = new Location((Location) msg.obj);
mListener.onLocationChanged(location);
break;
..... cases for other msg.what are snipped .....

-- Kostya

Post by Kostya Vasilyev
Being able to specify a Looper in requestLocationUpdates seems to
imply that LocationManager uses Looper/Message mechanism to deliver
location updates to the application.
Using the UI Looper seems safe then, since location update messages
would be delivered to the main thread, decoded into Java callback
method calls, and invoked as usual.
--
Kostya Vasilyev -- http://kmansoft.wordpress.com

Post by ADRA
I could be wrong about this due to inexperience, but due to the nature
of the looper, if you put it on the main looper and the GPS decides to
randomly disappear for seconds then the GUI freezes along with it. I
don't know if that really happen in reality, but I imagine the
possibility could occur. If you want to make sure that the location
class MyLocThread extends Thread
{
public MyLocThread ()
{
setDaemon(true);
setName("LocationThread");
}
public void run()
{
Looper.prepare();
lm.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
0L,
0L,
locListenerGPS,
Looper.getLooper()
);
Looper.loop();
}
}

Is there anything wrong with specifyi...

--
Kostya Vasilyev -- WiFi Manager + pretty widget -- http://kmansoft.wordpress.com

[damodhar meshran]

why u used loop update-location lister update location automatically

Post by Pent
Is there anything wrong with specifying the main thread looper to
lm.requestLocationUpdates(
LocationManager.GPS_PROVIDER,
0L,
0L,
locListenerGPS,
Looper.getMainLooper()
);
(call is made from a non-UI thread)
Am I going to start getting weird unexplicable errors in other places
due to the looper voodoo ?
Thanks,
Pent
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