调用onLocationChanged时，应用程序崩溃。 Campus_guide_Databasehelper是我处理数据库的类。当有位置更改时，我想从数据库中获取数据并将数据库结果与新位置进行比较;但是，这不起作用。
我的代码如下所示;请帮我解决这个错误。
public class GPSTracker extends Service implements LocationListener{
public Context mContext;
// flag for GPS status
boolean isGPSEnabled = false;
// flag for network status
boolean isNetworkEnabled = false;
boolean canGetLocation = false;
Location location; // location
double latitude; // latitude
double longitude; // longitude
// Campus_guide_Databasehelper cgh=new Campus_guide_Databasehelper(this);
// The minimum distance to change Updates in meters
private static final long MIN_DISTANCE_CHANGE_FOR_UPDATES = 0; // 10 meters
// The minimum time between updates in milliseconds
private static final long MIN_TIME_BW_UPDATES = 1000 *50; // 5 sec
// 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) {
// no network provider is enabled
this.canGetLocation=false;
} 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) {
Log.d("Network", "Network get location");
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;
}
Campus_guide_Databasehelper cgh;//=new Campus_guide_Databasehelper(mContext);
@Override
public void onLocationChanged(Location arg0) {
// Toast.makeText(mContext,String.valueOf(latitude), Toast.LENGTH_LONG).show();
Toast.makeText(mContext,"location changed", Toast.LENGTH_LONG).show();
cgh=new Campus_guide_Databasehelper(getApplicationContext());
Location curr_loc=new Location("");
Location dest_loc=new Location("");
float bearing=0;
String data=cgh.Nearest_point(latitude, longitude);
String[] split=data.split(":");
for(int i=1;i<split.length;i++)
{
String [] fur_split=split[i].split(" ");
Double llti=Double.parseDouble(fur_split[0]);
Double llong=Double.parseDouble(fur_split[1]);
dest_loc.setLatitude(llti);
dest_loc.setLongitude(llong);
bearing=curr_loc.bearingTo(dest_loc);
Toast.makeText(this,split[i-1], Toast.LENGTH_LONG).show();
Toast.makeText(this,String.valueOf(bearing), Toast.LENGTH_LONG).show();
i++;
}
}
@Override
public void onProviderDisabled(String arg0) {
// TODO Auto-generated method stub
}
@Override
public void onProviderEnabled(String arg0) {
// TODO Auto-generated method stub
}
@Override
public void onStatusChanged(String arg0, int arg1, Bundle arg2) {
// TODO Auto-generated method stub
}
@Override
public IBinder onBind(Intent arg0) {
// TODO Auto-generated method stub
return null;
}
/**
* 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 if best network provider
* @return boolean
* */
public boolean canGetLocation() {
return this.canGetLocation;
}
/**
* Function to show settings alert dialog
* */
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?");
// Setting Icon to Dialog
//alertDialog.setIcon(R.drawable.delete);
// 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();
}
/**
* Stop using GPS listener
* Calling this function will stop using GPS in your app
* */
public void stopUsingGPS(){
if(locationManager != null){
locationManager.removeUpdates(GPSTracker.this);
}
}
}