android - FusedLocation getLastLocation() 返回 null

Question

我知道这个问题已经有几个答案，但不幸的是我是一个初学者，我找不到这个问题的正确解决方案。该getLastKnowPosition方法没有返回任何内容。我该如何解决这个问题？我需要设备的当前位置。

已编辑我现在正在尝试评论中发布的解决方案。

代码

public class IntellySearch extends FragmentActivity implements OnMapReadyCallback {

private GoogleMap mMap;
private LocationManager locationManager;
private double posLat;
private double posLng;
private LatLng position;
private Marker mPosition;
private int numero = 1;
private FusedLocationProviderClient mFusedLocationClient;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_intelly_search);
    // Obtain the SupportMapFragment and get notified when the map is ready to be used.
    SupportMapFragment mapFragment = (SupportMapFragment) getSupportFragmentManager()
            .findFragmentById(R.id.map);
    mapFragment.getMapAsync(this);

    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
        return;
    }

    mFusedLocationClient = LocationServices.getFusedLocationProviderClient(this);
    mFusedLocationClient.getLastLocation().addOnSuccessListener(this, new OnSuccessListener<Location>() {
        @Override
        public void onSuccess(Location location) {
            if (location != null){
                posLat = location.getLatitude();
                posLng = location.getLongitude();
            }
        }
    }).addOnFailureListener(new OnFailureListener() {
        @Override
        public void onFailure(@NonNull Exception e) {
            Log.d("IntActivity", "Error getting last GPS location");
            e.printStackTrace();
        }
    });



    startGPS();
}


@Override
public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    // Add a marker in Sydney and move the camera
    LatLng duomo = new LatLng(43.773251, 11.255474);

    //mMap.moveCamera(CameraUpdateFactory.newLatLng(duomo));
    mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(duomo, 18f));
}


public void startGPS() {

    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED
            && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {

        ActivityCompat.requestPermissions(this, new String[]{Manifest.permission.ACCESS_FINE_LOCATION}, 5);
    }


    locationManager.requestLocationUpdates(LocationManager.GPS_PROVIDER, 3000, 5, new LocationListener() {
        @Override
        public void onLocationChanged(Location location) {
            posLat = location.getLatitude();
            posLng = location.getLongitude();

            position = new LatLng(posLat, posLng);

            if (mPosition != null) {
                mPosition.remove();
            }

            mPosition = mMap.addMarker(new MarkerOptions().position(position).title("Your position"));
            if (numero < 2) {
                mMap.moveCamera(CameraUpdateFactory.newLatLngZoom(position, 18));
                numero = 30;
            }
            mMap.moveCamera(CameraUpdateFactory.newLatLng(position));

        }

        @Override
        public void onStatusChanged(String s, int i, Bundle bundle) {

        }

        @Override
        public void onProviderEnabled(String s) {

        }

        @Override
        public void onProviderDisabled(String s) {

        }
    });

}

stacktrace 引用了两行代码：

第一的

public void onLocationChanged(Location location) {
            posLat = location.getLatitude();
            posLng = location.getLongitude();

            position = new LatLng(posLat, posLng);

            if (mPosition != null) {
                mPosition.remove();
            }

第二

public void onMapReady(GoogleMap googleMap) {
    mMap = googleMap;

    // Add a marker in Sydney and move the camera
    LatLng duomo = new LatLng(43.773251, 11.255474);

    //mMap.moveCamera(CameraUpdateFactory.newLatLng(duomo));
    mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(duomo, 18f));
}

堆栈跟踪

2019-01-31 11:10:30.269 7441-7441/com.icloud.andreadimartino.bellini I/Google Maps Android API: Google Play services client version: 12211000
2019-01-31 11:10:30.275 7441-7441/com.icloud.andreadimartino.bellini I/Google Maps Android API: Google Play services package version: 13280022
2019-01-31 11:10:30.311 1368-1411/? W/audio_hw_generic: Hardware backing HAL too slow, could only write 0 of 720 frames
2019-01-31 11:10:30.463 7441-7441/com.icloud.andreadimartino.bellini E/art: The String#value field is not present on Android versions >= 6.0
2019-01-31 11:10:30.896 7441-7441/com.icloud.andreadimartino.bellini E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.icloud.andreadimartino.bellini, PID: 7441
    java.lang.RuntimeException: Unable to start activity ComponentInfo{com.icloud.andreadimartino.bellini/com.icloud.andreadimartino.bellini.IntellySearch}: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.location.LocationManager.requestLocationUpdates(java.lang.String, long, float, android.location.LocationListener)' on a null object reference
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2646)
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2707)
        at android.app.ActivityThread.-wrap12(ActivityThread.java)
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1460)
        at android.os.Handler.dispatchMessage(Handler.java:102)
        at android.os.Looper.loop(Looper.java:154)
        at android.app.ActivityThread.main(ActivityThread.java:6077)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)
     Caused by: java.lang.NullPointerException: Attempt to invoke virtual method 'void android.location.LocationManager.requestLocationUpdates(java.lang.String, long, float, android.location.LocationListener)' on a null object reference
        at com.icloud.andreadimartino.bellini.IntellySearch.startGPS(IntellySearch.java:104)
        at com.icloud.andreadimartino.bellini.IntellySearch.onCreate(IntellySearch.java:79)
        at android.app.Activity.performCreate(Activity.java:6662)
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1118)

我如何解决它？

标签： androidlocation