有很多类似的问题,但我没有找到任何解决我的问题.
setUpMap方法是:
private void setUpMap() {
BitmapDescriptor iconm = BitmapDescriptorFactory.fromResource(R.drawable.m);
BitmapDescriptor iconc = BitmapDescriptorFactory.fromResource(R.drawable.c);
// Enable MyLocation Layer of Google Map
mMap.setMyLocationEnabled(true);
// Get LocationManager object from System Service LOCATION_SERVICE
LocationManager locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
// Create a criteria object to retrieve provider
Criteria criteria = new Criteria();
// Get the name of the best provider
String provider;
provider = locationManager.getBestProvider(criteria,true);
// Get Current Location
Location myLocation = locationManager.getLastKnownLocation(provider);
// getting GPS status
boolean isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
// getting network status
boolean isNWEnabled = locationManager.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
if (!isNWEnabled)
{
AlertDialog.Builder dialog = new AlertDialog.Builder(this);
dialog.setMessage(getString(R.string.askposition) );
dialog.setPositiveButton(getString(R.string.settings), new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface paramDialogInterface, int paramInt) {
// TODO Auto-generated method stub
startActivityForResult(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS), 100);
}
});
dialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
@Override
public void onClick(DialogInterface paramDialogInterface, int paramInt) {
// TODO Auto-generated method stub
}
});
dialog.show();
// no network provider is enabled
Log.e("Current Location", "Current Lat Lng is Null");
}
else
{
// if GPS Enabled get lat/long using GPS Services
if (isGPSEnabled){
if (myLocation == null) {
if (locationManager != null) {
myLocation = locationManager.getLastKnownLocation(LocationManager.GPS_PROVIDER);
double latitude = myLocation.getLatitude();
double longitude = myLocation.getLongitude();
LatLng latlng = new LatLng(latitude, longitude);
//myLocation = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
//double latitude = myLocation.getLatitude();
//double longitude = myLocation.getLongitude();
//String lati = String.valueOf(latitude);
//String longi = String.valueOf(longitude);
// Create a LatLng object for the current location
//LatLng latlng = new LatLng(latitude, longitude);
// set map type
//mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
//CameraPosition cameraPosition = new CameraPosition.Builder().target(latlng).zoom(12).build();
//mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
// Show the current location in Google Map
// mMap.moveCamera(newLatLng(latlng));
// Zoom in the Google Map
//mMap.animateCamera(CameraUpdateFactory.zoomTo(12));
}
}
}
else {
// First get location from Network Provider
if (isNWEnabled) {
if (myLocation == null) {
if (locationManager != null) {
myLocation = locationManager.getLastKnownLocation(LocationManager.NETWORK_PROVIDER);
double latitude = myLocation.getLatitude();
double longitude = myLocation.getLongitude();
LatLng latlng = new LatLng(latitude, longitude);
//double latitude = myLocation.getLatitude();
//double longitude = myLocation.getLongitude();
// Create a LatLng object for the current location
//LatLng latlng = new LatLng(latitude, longitude);
// set map type
//mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
// Zoom in the Google Map
//CameraPosition cameraPosition = new CameraPosition.Builder().target(latlng).zoom(12).build();
//mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
//mMap.animateCamera(CameraUpdateFactory.zoomTo(12));
// Show the current location in Google Map
//mMap.moveCamera(newLatLng(latlng));
}
}
}}
}
double latitude = myLocation.getLatitude();
double longitude = myLocation.getLongitude();
LatLng latlng = new LatLng(latitude, longitude);
CameraPosition cameraPosition = new CameraPosition.Builder().target(latlng).zoom(11).build();
mMap.setMapType(GoogleMap.MAP_TYPE_NORMAL);
mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition));
当我第一次将应用程序从Android Studio运行到我的设备时它工作正常,如果我关闭并重新启动应用程序也可以正常工作.
但是当我重新启动智能手机时,它会给我NullPointerException @ double latitude = myLocation.getLatitude();
从那一刻起它总是崩溃.
我该怎么办呢?
评论的代码行几乎没有尝试过.同样的问题.
任何帮助将非常感激.
提前致谢.
解决方法:
我认为你的问题的解决方法是使用PASSIVE_PROVIDER.
示例代码:
LocationManager locationManager = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 2000, 10, locationListener);
myLocation = locationManager.getLastKnownLocation(LocationManager.PASSIVE_PROVIDER);
double longitude = myLocation.getLongitude();
double latitude = myLocation.getLatitude();
private final LocationListener locationListener = new LocationListener() {
public void onLocationChanged(Location location) {
longitude = location.getLongitude();
latitude = location.getLatitude();
}
}