LocationManager returns 空经度与 getLastKnownLocation 在 Android

Question

我有一个代码应该 return 用户位置，但经度保持 returning null，结果我的应用程序不断崩溃。我该如何防止这种情况？

//get the user longitude and latitude
LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE); 
Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
double longitude = location.getLongitude();
double latitude = location.getLatitude();

Geocoder geocoder;  //return meaningful data from user location
List<Address> addresses;
geocoder = new Geocoder(this, Locale.getDefault());
addresses = geocoder.getFromLocation(latitude, longitude, 1);
address = addresses.get(0).getAddressLine(0);
city = addresses.get(0).getLocality();

Answer 1

添加支票。

if (location != null) {
    latitude = location.getLatitude();
    longitude = location.getLongitude();
}

至于为什么它没有返回值，您需要添加一些日志记录。

要获得更完整的解决方案，试试这个：

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 destination 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;
}

在此实现中，这是我从我的活动中调用的 class 中的方法。以及在不再需要资源后释放资源所需的代码。

例如：

/**
 * Stop using GPS listener
 * Calling this function will stop using GPS in your app
 */
public void stopUsingGPS() {
    if (locationManager != null) {
        locationManager.removeUpdates(LocFinder.this);
    }
}

免责声明 请注意，这只是所需代码的一部分，用于协助实现定位服务。资源在不使用时需要释放，定位服务的使用与项目的所有其他方面一样需要在整个应用程序的程序流程中进行管理。

查看 Getting the Last Known Location or Android Location API - Tutorial or Android - Location Based Services 以更全面地实施定位服务。

LocationManager returns 空经度与 getLastKnownLocation 在 Android

LocationManager returns null longitude with getLastKnownLocation in Android

java

android

android-location