I've been trying some tutorials and basic exercises with Google Maps V2 and I'm stuck with something happening to my "setOnMyLocationChangeListener" method.
I'm running the following code:
this.mMap.setOnMyLocationChangeListener(new OnMyLocationChangeListener() {
#Override
public void onMyLocationChange(Location location) {
int lat = (int) (location.getLatitude() * 1E6);
int lon = (int) (location.getLongitude() * 1E6);
Toast.makeText(
GoogleMapsV2_Interact.this,
"Coordss\n" + "Lat: " + lat + "\n" + "Lon: " + lon + "\n" ,
Toast.LENGTH_SHORT).show();
Log.d(TAG, "Event OnMyLocationChangeListener.");
}
});
If I understand correct this whole event is supposed to trigger only when the Location of the "My Location blue dot shown on the map" changes... but everytime I run the code on my devide I keep getting spamed with the toast of my code like the event is being triggered nonstop.
Is there something I'm missing , or something I'm not understanding ? I thought I was supposed to see my toasts only and only after a location change for the blue dot.
The documentation states that
Called when the Location of the My Location dot has changed (be it latitude/longitude, bearing or accuracy).
Maybe your bearing or accuracy is changing all the time - print them with the coordinates into the LogCat and see what's different from the previous log statements.
Related
In my Android application i need to get the traveled road with car and i check it with google android directions API and GPS.
But the problem is that some times the GPS location is not precise and i can get an error of 10Km for some lecture and that means that in a total travel of 150km my "distance traveled" can be 250km and it's wrong!
Yesterday i test it in highway and the problem is that when the marker is located out from highway, the calculation of distance traveled from my current position and the last marker located by road is very wrong (in this case out of the highway).
There is some best way for getting traveled distance with car using the phone?
Maybe some better code for getting more precise GPS position?
Here is my code:
private void getUserLocation() {
Log.d(TAG, "getUserLocation()");
checkLocationPermission();
mFusedLocationClient.getLastLocation()
.addOnSuccessListener(getActivity(), new OnSuccessListener<Location>() {
#Override
public void onSuccess(Location location) {
// Got last known location. In some rare situations this can be null.
if (location != null) {
// Logic to handle location object
String stringStartLat, stringStartLng;
double lat = location.getLatitude();
double lng = location.getLongitude();
//Start position of device
if (travelInfo.getStartLat() == 0 && travelInfo.getStartLng() == 0) {
travelInfo.setStartLat(lat);
travelInfo.setStartLng(lng);
//Set lastcoordinates equals to start
travelInfo.setLastLat(lat);
travelInfo.setLastLng(lng);
}
//Current position of device
travelInfo.setCurrentLat(lat);
travelInfo.setCurrentLng(lng);
stringStartLat = Double.toString(travelInfo.getStartLat());
stringStartLng = Double.toString(travelInfo.getStartLng());
//Set the TextView in the fragment with start coordinates
Log.d(TAG,"LatitudeStart: " + stringStartLat);
Log.d(TAG,"LongitudeStart: " + stringStartLng);
if (startMarker == null) {
//Add the user location to the map with a marker
LatLng userLoction = new LatLng(travelInfo.getStartLat(), travelInfo.getStartLng());
startMarker = googleMap.addMarker(new MarkerOptions()
.position(userLoction)
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_ORANGE))
.title("Start Position")
.snippet("Show the start position of user"));
// For zooming automatically to the location of the marker
CameraPosition cameraPosition = new CameraPosition.Builder().target(userLoction).zoom(9).build();
googleMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
} else {
LatLng currentLocation = new LatLng(travelInfo.getCurrentLat(), travelInfo.getCurrentLng());
currentPositionMarker = googleMap.addMarker(new MarkerOptions()
.position(currentLocation)
.icon(BitmapDescriptorFactory.defaultMarker(BitmapDescriptorFactory.HUE_YELLOW))
.title("Current Position")
.snippet("Show the current position of user during travel"));
// For zooming automatically to the location of the marker
CameraPosition cameraPosition = new CameraPosition.Builder().target(currentLocation).zoom(11).build();
googleMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
}
if (travelInfo.getEndLat() != 0 && travelInfo.getEndLng() != 0) {
Log.i(TAG, "Dentro if userlocation");
//Get total distance of travel
getTotalDistanceTime(travelInfo);
//Get the percurred distance from last known coordinates
getPercurredDistance(travelInfo);
}
}
}
});
}
And getpercurredDistance use google direction API with this url
String url = "https://maps.googleapis.com/maps/api/directions/json?origin=" + obj.getLastLat() + "," + obj.getLastLng() + "&destination=" + obj.getCurrentLat() + "," + obj.getCurrentLng() + "&mode=driving&key=AI*******************I";
For getting distance traveled from last marker and current position marker.
But some times it put the localized position too far from real position... how avoid this?
EDIT
The method that i use is good for my work? mFusedLocationClient.getLastLocation()
There is no possibilities to get more precise GPS position from GPS sensor of android device, but you can filter "wrong" points this ways:
1) for each travel point get several values of Lat and Lng, discard the minimum and maximum and average the remaining ones;
2) log timestamps of each travel point and compare it for two neighboring points: speed (distance between that two points divided by time interval of that points) grater than max. car speed (e.g. 250 km/h) that means the second point is wrong (if first point is good of course).
3) use Google Maps Roads API to find best-fit road geometry for a given set of GPS coordinates.
Also take a look at this question.
For real-time location purposes, location updates allow you to request location updates at different intervals. See the android developer location documentation. The function you want is FusedLocationProviderClient.requestLocationUpdates.
There is no reason GPS (or any other widely used location technology) should ever give you 10km error for a single location estimate. If you are getting this, there is a large mismatch between when you the location estimate was made and when you are requesting it.
How can I get the exact Latitude and Longitude? I only get whole numbers. From my understanding, in order to get down to the meter I need to get down to 5 decimal places. I have tried the horizontal and vertical accuracy but they don't match my phones GPS reading.
How can I get an exact GPS reading with Geolocation API, Down to the meter?
here is my code
var my_geo:Geolocation = new Geolocation();
my_geo.setRequestedUpdateInterval(2000);
my_geo.addEventListener(GeolocationEvent.UPDATE, onGeoUpdate);
function onGeoUpdate(e:GeolocationEvent):void
{
gpsLat1 = (e.latitude);
gpsLon1 = (e.longitude);
gpsHeading = (e.heading);
gpsHorAcc = (e.horizontalAccuracy);
gpsVerAcc = (e.verticalAccuracy);
gpsCheck = 2;
my_txt.text = "My Latitude is "+ gpsLat1 + " and my Longitude is "+ gpsLon1 + " Bearing is " + gpsHeading+ " HorAcc "+ gpsHorAcc+ " VertAcc "+gpsVerAcc;
}
Make sure your variables (gpsLat1, gpsLon1, gpsHeading, etc.) are of type Number and not a uint or int. Unsigned Integers and Integers only allow for whole numbers, whereas Number is the equivalent of float in most other languages (and allows for incredibly larger values, as well). If you save a decimal to an integer, it is rounded off/floored (I can't remember which), which sounds exactly like the problem you are having.
Alternatively, the API is restricted by the hardware you are testing on. If the hardware only returns a certain value for GPS coordinates, AIR cannot be any more precise. Odds are this is not the issue since a whole lat long point can be miles and miles in distance, meaning any device with that inaccurate of a GPS chip is absolutely useless.
Try this:
function onGeoUpdate(e:GeolocationEvent):void
{
gpsLat1 = (e.latitude.toString());
gpsLon1 = (e.longitude.toString());
gpsHeading = (e.heading.toString());
gpsHorAcc = (e.horizontalAccuracy.toString());
gpsVerAcc = (e.verticalAccuracy.toString());
gpsCheck = 2;
my_txt.text = "My Latitude is "+ gpsLat1 + " and my Longitude is "+ gpsLon1 + " Bearing is " + gpsHeading+ " HorAcc "+ gpsHorAcc+ " VertAcc "+gpsVerAcc;
}
I'm wrinting a application and I have to show the distance covered while I'm running.
I use the function "public void onLocationChanged" of the LocationListener. When the user tap a botton and start running I want to show the distance he covered updated to the point in which he is located.
I've written this code:
public void onLocationChanged(Location location) {
if(location != null) {
if(location.hasSpeed()){
if(latitude1 == 0 && longitude1 == 0){
latitude1 = (location.getLatitude()*Math.PI)/180;
longitude1 = (location.getLongitude()*Math.PI)/180;
} else{
latitude2 = (location.getLatitude()*Math.PI)/180;
longitude2 = (location.getLongitude()*Math.PI)/180;
distance = (6372.795477598)*Math.acos(Math.sin(latitude1)
*Math.sin(latitude2)+Math.cos(latitude1)
*Math.cos(latitude2)*Math.cos(longitude1-longitude2));
sumDistance += distance;
latitude1 = latitude2;
longitude1 = longitude2;
}
tv.setText("Distance covered=" + sumDistance + " m");
}
}
}
Is it accurated?
Just a Suggestion:
Store the Latitude and Longitude of the start location and the end location when the user clicks the appropriate button.
and then you could use distanceBetween or distanceTo to get the distance between those two geoPoints.
P.S: This may not work if the user will start and end his run at the same point ;)
Addition:
Check this tutorial:
Recently google has improved its location based API's. They have fused the sensors with the location based api's to share examples of how location can be made more accurate (about 4 times more effective) and consume much lesser power (10 times lesser).
Some interesting links for you to go through will be this and video google io.
SO link for how to use the API's here
I am building a GPS Android application whereby it retrieves the nearest places based on the user's current location. At first, I detect both GPS and network to see if they are enabled. If both are enabled I would use GPS first because it is the most accurate, and for my application it is safe to assume they are outside, therefore, retrieving GPS should not take too long. Nevertheless, there are always situations when GPS takes a long time. How do I therefore implement a way to switch over to NETWORK_PROVIDER if GPS takes over, for example, 2 minutes?
This is my code right now:
I check if GPS or internet is enabled.
if(!GPSEnabled && !networkEnabled)
{
Toast.makeText(this, "Error: This application requires a GPS or network connection",
Toast.LENGTH_SHORT).show();
}
else
{
if(GPSEnabled)
{
locManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 0, 0, this);
}
else if(networkEnabled)
{
System.out.println("Getting updates from network provider");
locManager.requestLocationUpdates(LocationManager.NETWORK_PROVIDER, 0, 0, this);
}
}
This is the onLocationChanged method. I get the lat/lng values and then send them off to my server and then do appropriate stuff with it.
public void onLocationChanged(Location location)
{
//Get coordinates
double lat = (location.getLatitude());
double lng = (location.getLongitude());
Log.d("MainActivity", "got location: " + lat + ": " + lng);
//get nearest locations
new GetLocations().execute(SharedVariables.root + SharedVariables.locationsController + SharedVariables.getNearestMethod + lat + "/" + lng);
// Zoom in, animating the camera after the markers have been placed
map.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(lat, lng), 10));
System.out.println("lat = " + lat + ", lng = " + lng);
//Stop listening for updates. We only want to do this once.
locManager.removeUpdates(this);
}
What would I need to add to switch over to Network or GPS if either one takes too long?
I'd recommend to use both providers at the same time and determine more accurate location using, for example, isBetterLocation() function from this article: http://developer.android.com/guide/topics/location/strategies.html. In this case users won't have to wait 2 minutes to use your app, if GPS is slow. At first, you'll use network updates, and then, when GPS fixes are obtained, more accurate locations.
Here is my app:
public class HlavnaAktivita extends MapActivity implements LocationListener {
...
public void onLocationChanged(Location location) {
Log.w("myApp", String.valueOf(location.getLatitude()));
}
When I give to emulator for example 48.590007 and 17.824579, it just write "17.0". I tried http://www.androidcompetencycenter.com/?s=GPS this tutorial (from StackOverflow) and when I run that app, it write good postition, but on map is just rounded position (17, 48) (position according to maps.google.com is good, but on map is cca 100km wrong).
What could be the problem? I tried a lot of tutorials but it's still not working.
To get the exact position on the map you need 2 parameters:
Latitude and Longitude of a Point.
GeoPoint accepts latitude and longitude in microdegrees so try to create your point like this to get better accuracy:
double lati = location.getLatitude();
double longi = location.getLongitude();
GeoPoint geo_point= new GeoPoint((int)(lati * 1e6),(int)(longi * 1e6));
It converts somewhere your number to int. To avoid it try someting like:
Log.w("myApp", String.valueOf((float) location.getLatitude()));
This was just my mistake - I forget to add (). Sorry.