无法在 android 中获取用户 currentLocation

Question

我将在地图中显示用户当前位置，但我在 onResume()(super.onResume()) 中出现以下错误：

 @Override
    public void onResume() {
        **super.onResume();**
        mapView.onResume();
        mGoogleApiClient.connect();
    }
     java.lang.NullPointerException: Attempt to invoke interface method 'void com.google.maps.api.android.lib6.d.fk.o()' on a null object reference

我的 class 扩展如下：

extends SupportMapFragment implements
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,LocationListener

onCreateView:

mapView=(MapView)view.findViewById(R.id.map);
        mapView.onCreate(savedInstanceState);

        map = mapView.getMap();
        mGoogleApiClient = new GoogleApiClient.Builder(mActivity)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .addApi(LocationServices.API)
                .build();
        mLocationRequest = LocationRequest.create()
                .setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY)
                .setInterval(10 * 1000)        // 10 seconds, in milliseconds
                .setFastestInterval(1 * 1000); // 1 second, in milliseconds

覆盖：

@Override
    public void onConnected(Bundle bundle) {
        Location location = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
        if (location == null) {
            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, this);
        }
        else {
            handleNewLocation(location);
        };
    }

    @Override
    public void onConnectionSuspended(int i) {

    }


    @Override
    public void onConnectionFailed(ConnectionResult connectionResult) {
        if (connectionResult.hasResolution()) {
            try {
                // Start an Activity that tries to resolve the error
                connectionResult.startResolutionForResult(mActivity, CONNECTION_FAILURE_RESOLUTION_REQUEST);
            } catch (IntentSender.SendIntentException e) {
                e.printStackTrace();
            }
        } else {
            Log.i("TAG", "Location services connection failed with code " + connectionResult.getErrorCode());
        }
    }
    private void handleNewLocation(Location location) {
        double currentLatitude = location.getLatitude();
        double currentLongitude = location.getLongitude();
        LatLng latLng = new LatLng(currentLatitude, currentLongitude);
        MarkerOptions options = new MarkerOptions()
                .position(latLng)
                .title("I am here!");
        map.addMarker(options);
        map.moveCamera(CameraUpdateFactory.newLatLng(latLng));
    }
@Override
    public void onLocationChanged(Location location) {
        handleNewLocation(location);
    }

我真的不知道这个错误，请帮助我。

Answer 1

我建议你使用外部文件来获取你的位置，这是代码。

package com.appadeus.homer.utilities;

import android.app.AlertDialog;
import android.app.Service;
import android.content.Context;
import android.content.DialogInterface;
import android.content.Intent;
import android.location.Location;
import android.location.LocationListener;
import android.location.LocationManager;
import android.os.Bundle;
import android.os.IBinder;
import android.provider.Settings;
import android.util.Log;

import com.mapbox.mapboxsdk.geometry.LatLng;

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
    public  boolean isLocationAlertShown = true;
    public boolean  comeBackAfterTurnGPSON = false;


    // 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 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;
                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;
    }

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

    /**
     * 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 return LatLng
     */
    public LatLng getLatLng() {
        LatLng newLatLng = null;
        if(location!=null)
        {
            newLatLng = new LatLng(location.getLatitude(), location.getLongitude());
            return newLatLng;
        }
        return  newLatLng;
    }

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

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

        // Setting Dialog Title
        //      alertDialog.

        // Setting Dialog Message
        alertDialog.setMessage("Please Turn on Location Services");

        // 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);
                comeBackAfterTurnGPSON = true;
            }
        });

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

    @Override
    public void onLocationChanged(Location location) {
        this.location = location;
    }

    @Override
    public void onProviderDisabled(String provider) {
    }

    @Override
    public void onProviderEnabled(String provider) {
    }

    @Override
    public void onStatusChanged(String provider, int status, Bundle extras) {
    }

    @Override
    public IBinder onBind(Intent arg0) {
        return null;
    }

}

首先通过

将您的对象植入

GPSTracker gps = new GPSTracker(context);

首先要使用它，您应该通过电话检查您的 gps 是否启用

if(gps.canGetLocation())
{
    //add your code here
    gps.getLocation()
}
else
{
   //show allert dialog to open setting
   gps.showSettingsAlert();
}

Answer 2

将此添加到您的 onCreateView():

super.onCreateView(inflater, container, savedInstanceState);

你的 onCreateView() 没有它就没用了。这就是为什么您的 mapView.onCreate(savedInstanceState); 可能没有被调用的原因。

确保初始化 mapView 对象 (new MapView)，它可能为空。

无法在 android 中获取用户 currentLocation

cannot get user currentLocation in android

android

google-maps-api-3

android-maps

android-mapview

android-maps-v2