Android谷歌地图V2当前位置纬度经度NullPointerException [英] Android Google Maps V2 current position latitude longitude NullPointerException
本文介绍了Android谷歌地图V2当前位置纬度经度NullPointerException的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
setUpMap方法是：
private void setUpMap（）{
BitmapDescriptor iconm = BitmapDescriptorFactory.fromResource（ R.drawable.m）;
BitmapDescriptor iconc = BitmapDescriptorFactory.fromResource（R.drawable.c）;
//启用Google Map的MyLocation图层
mMap.setMyLocationEnabled（true）;
//从系统服务LOCATION_SERVICE获取LocationManager对象
LocationManager locationManager =（LocationManager）getSystemService（Context.LOCATION_SERVICE）;
//创建一个标准对象来检索提供者
Criteria criteria = new Criteria（）;
//获取最佳提供者的名称
字符串提供者;
provider = locationManager.getBestProvider（criteria，true）;
//获取当前位置
位置myLocation = locationManager.getLastKnownLocation（provider）;
//获取GPS状态
boolean isGPSEnabled = locationManager.isProviderEnabled（LocationManager.GPS_PROVIDER）;
//获取网络状态
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自动生成的方法存根
startActivityForResult（new Intent（android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS），100）;
}
}）;
dialog.setNegativeButton（Cancel，new DialogInterface.OnClickListener（）{
@Override $ b $ public void onClick（DialogInterface paramDialogInterface，int paramInt）{
// TODO自动生成方法存根
}
}）;
dialog.show（）;
//未启用网络提供商
Log.e（当前位置，当前经纬度为空）;
}
else
{
//如果启用GPS，则使用GPS服务获取经纬度
if（isGPSEnabled）{
if（myLocation == null ）{
if（locationManager！= null）{
myLocation = locationManager.getLastKnownLocation（LocationManager.GPS_PROVIDER）;
double latitude = myLocation.getLatitude（）;
double longitude = myLocation.getLongitude（）;
LatLng latlng =新LatLng（纬度，经度）;
// myLocation = locationManager.getLastKnownLocation（LocationManager.NETWORK_PROVIDER）;
// double latitude = myLocation.getLatitude（）;
// double longitude = myLocation.getLongitude（）;
// String lati = String.valueOf（latitude）;
// String longi = String.valueOf（longitude）;
//为当前位置创建一个LatLng对象
// LatLng latlng = new LatLng（latitude，longitude）;
//设置地图类型
//mMap.setMapType（GoogleMap.MAP_TYPE_NORMAL）;
// CameraPosition cameraPosition = new CameraPosition.Builder（）。target（latlng）.zoom（12）.build（）;
//mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition））;
//在Google Map中显示当前位置
// mMap.moveCamera（newLatLng（latlng））;
//放大Google Map
//mMap.animateCamera(CameraUpdateFactory.zoomTo(12））;
$ b else {
//首先从网络供应商处获得位置
if（isNWEnabled）{
if（myLocation = = null）{
if（locationManager！= null）{
myLocation = locationManager.getLastKnownLocation（LocationManager.NETWORK_PROVIDER）;
double latitude = myLocation.getLatitude（）;
double longitude = myLocation.getLongitude（）;
LatLng latlng =新LatLng（纬度，经度）;
// double latitude = myLocation.getLatitude（）;
// double longitude = myLocation.getLongitude（）;
//为当前位置创建一个LatLng对象
// LatLng latlng = new LatLng（latitude，longitude）;
//设置地图类型
//mMap.setMapType（GoogleMap.MAP_TYPE_NORMAL）;
//放大Google Map
// CameraPosition cameraPosition = new CameraPosition.Builder（）。target（latlng）.zoom（12）.build（）;
//mMap.animateCamera(CameraUpdateFactory.newCameraPosition(cameraPosition））;
//mMap.animateCamera(CameraUpdateFactory.zoomTo(12））;
//在Google Map中显示当前位置
//mMap.moveCamera(newLatLng(latlng））;
}
}
}}
}
double latitude = myLocation.getLatitude（）;
double longitude = myLocation.getLongitude（）;
LatLng latlng =新LatLng（纬度，经度）;
CameraPosition cameraPosition = new CameraPosition.Builder（）。target（latlng）.zoom（11）.build（）;
mMap.setMapType（GoogleMap.MAP_TYPE_NORMAL）;
mMap.animateCamera（CameraUpdateFactory.newCameraPosition（cameraPosition））;
当我第一次从Android Studio运行应用程序到我的设备时，它工作正常，如果我关闭并重新启动应用程序。
但是当我重启我的智能手机时，它给了我NullPointerException @ double latitude = myLocation.getLatitude（）;
，从那一刻起它总是崩溃。
我该如何修复它？
评论的代码行几乎没有尝试。同样的问题。
任何帮助将不胜感激。
在此先感谢。
解决方案
我认为针对您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（）;
}
}
There are a lot of similar question but I don't find any solution for my problem. The setUpMap method is:
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));
It works fine when I first Run the app from Android Studio to my device, also works fine if I close and restart the application.
But when I reboot my smartphone it gives me NullPointerException @ double latitude = myLocation.getLatitude();
and from that moment it crash always.
How could I fix it?
The commented code lines are about few attempts. Same problem at all.
Any help would be much appreciated.
Thanks in advance.
解决方案
I think a workaround for your problem is to use PASSIVE_PROVIDER.
Sample code:
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();
}
}
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