GPS Location not being changed android

问题:

I'm writing a simple app that needs to set the current GPS coordinates from let's say point A, then travel to another point B and have it detect the coordinates at point B. I am able to get point A coordinates no problem. I'm just not getting it to detect the coordinates at point B, it reads the same coordinates as the ones at point A. I've got the app installed on my phone, and I am driving a mile between points. My manifest file includes every possible permission for location.

Here is the activity code.

public class GPSTrackingActivity extends Activity {

Button btnShowLocation;
Button btnShowEndLocation;

// GPSTracker class
GPSTracker gps;

TextView tvIntialLocation;
TextView tvEndLocation;

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    myDBHelper = new DataBaseHelper(GPSTrackingActivity.this);
    tvIntialLocation = (TextView)findViewById(R.id.tvIntialLocation);
    tvEndLocation = (TextView)findViewById(R.id.tvEndLocation);

    // create class object
    gps = new GPSTracker(GPSTrackingActivity.this);     


    btnShowLocation = (Button) findViewById(R.id.btnShowLocation);
    btnShowEndLocation = (Button)findViewById(R.id.btnEndLocation);

    // show location button click event
    btnShowLocation.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {

            // check if GPS enabled
            if(gps.canGetLocation()){

                double latitude = gps.getLatitude();
                double longitude = gps.getLongitude();
                tvIntialLocation.setText("Start Location is - \nLat: " + latitude + "\nLong: " + longitude);

               }else{
                // can't get location
                // GPS or Network is not enabled
                // Ask user to enable GPS/network in settings
                gps.showSettingsAlert();
            }

        }
    });

 // show location button click event
    btnShowEndLocation.setOnClickListener(new View.OnClickListener() {

        @Override
        public void onClick(View arg0) {

            // check if GPS enabled
            if(gps.canGetLocation()){

                double latitude = gps.getLatitude();
                double longitude = gps.getLongitude();
                tvEndLocation.setText("End Location is - \nLat: " + latitude + "\nLong: " + longitude);

            }else{
                // can't get location
                // GPS or Network is not enabled
                // Ask user to enable GPS/network in settings
                gps.showSettingsAlert();
            }

        }
    });

}

}

Here is the class setting up the GPS Tracker class. I am not sure if the onLocationChanged is getting called, I didn't see any Toast messages when the location changed while I was driving.

public class GPSTracker extends Service implements LocationListener {

private final Context mContext;

// flag for GPS status
boolean isGPSEnabled = false;

// flag for network status
boolean isNetworkEnabled = false;

// flag for GPS status
boolean canGetLocation = false;

Location location; // location
double latitude; // latitude
double longitude; // longitude

// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 10; // 10 meters

// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 * 60 * 1; // 1 minute

// Declaring a Location Manager
protected LocationManager locationManager;

public GPSTracker(Context context) {
    this.mContext = context;
    getLocation();
}

public Location getLocation() {
    try {
        locationManager = (LocationManager) mContext
                .getSystemService(LOCATION_SERVICE);

        // getting GPS status
        isGPSEnabled = locationManager
                .isProviderEnabled(LocationManager.GPS_PROVIDER);

        // getting network status
        isNetworkEnabled = locationManager
                .isProviderEnabled(LocationManager.NETWORK_PROVIDER);

        if (!isGPSEnabled && !isNetworkEnabled) {
            // no network provider is enabled
        } else {
            this.canGetLocation = true;
            // First get location from Network Provider
            if (isNetworkEnabled) {
                locationManager.requestLocationUpdates(
                        LocationManager.NETWORK_PROVIDER,
                        MIN_TIME_BW_UPDATES,
                        MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                Log.d("Network", "Network");
                if (locationManager != null) {
                    location = locationManager
                            .getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
                    if (location != null) {
                        latitude = location.getLatitude();
                        longitude = location.getLongitude();

                    }
                }
            }
            // if GPS Enabled get lat/long using GPS Services
            if (isGPSEnabled) {
                if (location == null) {
                    locationManager.requestLocationUpdates(
                            LocationManager.GPS_PROVIDER,
                            MIN_TIME_BW_UPDATES,
                            MIN_DISTANCE_CHANGE_FOR_UPDATES, this);
                    Log.d("GPS Enabled", "GPS Enabled");
                    if (locationManager != null) {
                        location = locationManager
                                .getLastKnownLocation(LocationManager.GPS_PROVIDER);
                        if (location != null) {
                            latitude = location.getLatitude();
                            longitude = location.getLongitude();
                        }
                    }
                }
            }
        }

    } catch (Exception e) {
        e.printStackTrace();
    }

    return location;
}


/**
 * Function to get latitude
 * */
public double getLatitude(){
    if(location != null){
        latitude = location.getLatitude();
    }

    // return latitude
    return latitude;
}

/**
 * Function to get longitude
 * */
public double getLongitude(){
    if(location != null){
        longitude = location.getLongitude();
    }

    // return longitude
    return longitude;
}

/**
 * Function to check GPS/wifi enabled
 * @return boolean
 * */
public boolean canGetLocation() {
    return this.canGetLocation;
}


@Override
public void onLocationChanged(Location location) {
    location = getLocation();
    // Testing onLocationChanged:
    String hej1 = Double.toString(location.getLatitude());
    String hej2 = Double.toString(location.getLongitude());
    Toast.makeText(this, "Location: "+"Lat: " + hej1 + "Long: " + hej2,
            Toast.LENGTH_LONG).show();
}

/**
 * Function to show settings alert dialog
 * On pressing Settings button will lauch Settings Options
 * */
public void showSettingsAlert(){
    AlertDialog.Builder alertDialog = new AlertDialog.Builder(mContext);

    // Setting Dialog Title
    alertDialog.setTitle("GPS is settings");

    // Setting Dialog Message
    alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");

    // On pressing Settings button
    alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog,int which) {
            Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
            mContext.startActivity(intent);
        }
    });

    // on pressing cancel button
    alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
        public void onClick(DialogInterface dialog, int which) {
        dialog.cancel();
        }
    });

    // Showing Alert Message
    alertDialog.show();
}

}

Why is the second point not being updated to the current location? Start and End points show as the same GPS coordinates.

回答1:

Change the onLocationChanged to the code below

    @Override
    public void onLocationChanged(Location location) {
        this.location = location;
        // Testing onLocationChanged:
        String hej1 = Double.toString(location.getLatitude());
        String hej2 = Double.toString(location.getLongitude());
        Toast.makeText(this, "Location: "+"Lat: " + hej1 + "Long: " + hej2,
            Toast.LENGTH_LONG).show();
    }

You should prefix class members with m for example Location mLocation;

回答2:

You are using getLastKnownLocation that always does not work for getting update location.

I had same problem. Finally i solved it. You can use google FusedLocationApi for getting location update like google map app.

Code Sample in service:

 @Override
    public void onCreate() {
if (checkPlayServices()) {

            startFusedLocation();

            registerRequestUpdate(this);
        }
}

 private boolean checkPlayServices() {
        int resultCode = GooglePlayServicesUtil
                .isGooglePlayServicesAvailable(this);
        if (resultCode != ConnectionResult.SUCCESS) {
            if (GooglePlayServicesUtil.isUserRecoverableError(resultCode)) {
                Toast.makeText(getApplicationContext(),
                        "This device is supported. Please download google play services", Toast.LENGTH_LONG)
                        .show();
            } else {
                Toast.makeText(getApplicationContext(),
                        "This device is not supported.", Toast.LENGTH_LONG)
                        .show();

            }
            return false;
        }
        return true;
    }
 public void startFusedLocation() {
        if (mGoogleApiClient == null) {
            mGoogleApiClient = new GoogleApiClient.Builder(this).addApi(LocationServices.API)
                    .addConnectionCallbacks(new GoogleApiClient.ConnectionCallbacks() {
                        @Override
                        public void onConnectionSuspended(int cause) {
                        }

                        @Override
                        public void onConnected(Bundle connectionHint) {

                        }
                    }).addOnConnectionFailedListener(new GoogleApiClient.OnConnectionFailedListener() {

                        @Override
                        public void onConnectionFailed(ConnectionResult result) {

                        }
                    }).build();
            mGoogleApiClient.connect();
        } else {
            mGoogleApiClient.connect();
        }
    }

    public void stopFusedLocation() {
        if (mGoogleApiClient != null) {
            mGoogleApiClient.disconnect();
        }
    }

    public void registerRequestUpdate(final LocationListener listener) {
        mLocationRequest = LocationRequest.create();
        mLocationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);

        mLocationRequest.setInterval(1000); // every second
        //mLocationRequest.setFastestInterval(NOTIFY_INTERVAL/2);


        new Handler().postDelayed(new Runnable() {
            @Override
            public void run() {
                try {
                    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, listener);
                } catch (SecurityException e) {
                    e.printStackTrace();
                } catch (Exception e) {
                    e.printStackTrace();
                    if (!isGoogleApiClientConnected()) {
                        mGoogleApiClient.connect();
                    }

                    registerRequestUpdate(listener);


                }
            }
        }, 1000);
    }

    public boolean isGoogleApiClientConnected() {
        return mGoogleApiClient != null && mGoogleApiClient.isConnected();
    }

    @Override
    public void onLocationChanged(Location location) {      
        double lat = location.getLatitude();
        double lon = location.getLongitude();
        Toast.makeText(getApplicationContext(), "NEW LOCATION RECEIVED", Toast.LENGTH_LONG).show();


        String Provider=location.getProvider();

        Log.d("location", "IN ON LOCATION CHANGE, lat=" + lat + ", lon=" + lon);

        //locationManager.removeUpdates(this);

    }

    public void setFusedLatitude(double lat) {
        fusedLatitude = lat;
    }

    public void setFusedLongitude(double lon) {
        fusedLongitude = lon;
    }

    public double getFusedLatitude() {
        return fusedLatitude;
    }

    public double getFusedLongitude() {
        return fusedLongitude;
    }