所以我在我的活动课上遇到了称为空引用的错误 我仅在尝试将我的活动类加载到应用程序中时才收到此错误。我也收到请求的权限消息，授予权限后，出现此错误。请有人可以帮我吗？我现在要修复几个小时。
Attempt to read from field 'int com.google.android.gms.location.LocationRequest.a' on a null object reference
我不确定我哪里出错了..这是我的java类
public class Welcome extends FragmentActivity implements OnMapReadyCallback,
GoogleApiClient.ConnectionCallbacks,
GoogleApiClient.OnConnectionFailedListener,
LocationListener
{
private GoogleMap mMap;
// Play services
private static final int MY_PERMISSION_REQUEST_CODE = 7000;
private static final int PLAY_SERVICE_RES_REQUEST = 7001;
private LocationRequest mLocationRequest;
private GoogleApiClient mGoogleApiClient;
private Location mLastLocation;
private static int UPDATE_INTERVAL = 5000;
private static int FATEST_INTERVAL = 3000;
private static int DISPLACEMENT =10;
DatabaseReference drivers;
GeoFire geoFire;
Marker mCurrent;
MaterialAnimatedSwitch location_switch;
SupportMapFragment mapFragment;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_welcome);
// Obtain the SupportMapFragment and get notified when the map is ready to be used.
mapFragment = (SupportMapFragment) getSupportFragmentManager()
.findFragmentById(R.id.map);
mapFragment.getMapAsync(this);
//Initialize view
location_switch = (MaterialAnimatedSwitch)findViewById(R.id.location_switch);
location_switch.setOnCheckedChangeListener(new MaterialAnimatedSwitch.OnCheckedChangeListener() {
@Override
public void onCheckedChanged(boolean isOnline) {
if(isOnline) {
startLocationUpdates();
displayLocation();
Snackbar.make(mapFragment.getView(), "You are now Online!", Snackbar.LENGTH_SHORT)
.show();
}else
{
stopLocationUpdates();
mCurrent.remove();
Snackbar.make(mapFragment.getView(), "You are now Offline!", Snackbar.LENGTH_SHORT)
.show();
}
}
});
//Geo fire
drivers = FirebaseDatabase.getInstance().getReference("Drivers");
geoFire = new GeoFire(drivers);
setUpLocation();
}
//
@Override
public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
switch (requestCode)
{
case MY_PERMISSION_REQUEST_CODE:
if(grantResults.length > 0 && grantResults[0]==PackageManager.PERMISSION_GRANTED)
{
if(checkPlayServices()){
buildGoogleApiClient();
createLocationRequest();
if(location_switch.isChecked())
displayLocation();
}
}
}
}
private void setUpLocation() {
if(ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED )
{
// Request runtime permission
ActivityCompat.requestPermissions(this,new String[]{
Manifest.permission.ACCESS_COARSE_LOCATION,
Manifest.permission.ACCESS_FINE_LOCATION,
}, MY_PERMISSION_REQUEST_CODE);
}
else
{
if(checkPlayServices()){
buildGoogleApiClient();
createLocationRequest();
if(location_switch.isChecked())
displayLocation();
}
}
}
private void createLocationRequest() {
LocationRequest locationRequest = LocationRequest.create();
locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);
locationRequest.setInterval(5000);
locationRequest.setFastestInterval(1000);
}
private void buildGoogleApiClient() {
mGoogleApiClient = new GoogleApiClient.Builder(this)
.addConnectionCallbacks(this)
.addOnConnectionFailedListener(this)
.addApi(LocationServices.API)
.build();
mGoogleApiClient.connect();
}
private boolean checkPlayServices() {
int resultCode = GooglePlayServicesUtil.isGooglePlayServicesAvailable(this);
if(resultCode != ConnectionResult.SUCCESS)
{
if (GooglePlayServicesUtil.isUserRecoverableError(resultCode))
GooglePlayServicesUtil.getErrorDialog(resultCode, this, PLAY_SERVICE_RES_REQUEST).show();
else{
Toast.makeText(this, "This device is not supported", Toast.LENGTH_SHORT).show();
finish();
}
return false;
}
return true;
}
private void stopLocationUpdates() {
if(ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED )
{
return;
}
LocationServices.FusedLocationApi.removeLocationUpdates(mGoogleApiClient, this);
}
private void displayLocation() {
if(ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED )
{
return;
}
mLastLocation = LocationServices.FusedLocationApi.getLastLocation(mGoogleApiClient);
if(mLastLocation != null)
{
if(location_switch.isChecked())
{
final double latitude = mLastLocation.getLatitude();
final double longitude = mLastLocation.getLongitude();
//Update to firebase
geoFire.setLocation(FirebaseAuth.getInstance().getCurrentUser().getUid(), new GeoLocation(latitude, longitude), new GeoFire.CompletionListener() {
@Override
public void onComplete(String key, DatabaseError error) {
//Add marker
if(mCurrent != null)
mCurrent.remove(); // remove already marker
mCurrent = mMap.addMarker(new MarkerOptions()
.icon(BitmapDescriptorFactory.fromResource(R.drawable.car))
.position(new LatLng(latitude,longitude))
.title("You"));
//Move camera to this location
mMap.animateCamera(CameraUpdateFactory.newLatLngZoom(new LatLng(latitude,longitude),15.0f));
//Draw animation rotate marker
rotateMarker(mCurrent,-360,mMap);
}
});
}
else {
Log.d("ERROR","Cannot get your location");
}
}
}
private void rotateMarker(final Marker mCurrent, final float i, GoogleMap mMap) {
final Handler handler = new Handler();
final long start = SystemClock.uptimeMillis();
final float startRotation = mCurrent.getRotation();
final long duration = 1500;
final Interpolator interpolator = new LinearInterpolator();
handler.post(new Runnable() {
@Override
public void run() {
long elapsed = SystemClock.uptimeMillis() - start;
float t = interpolator.getInterpolation((float)elapsed/duration);
float rot = t*i+(1-t)*startRotation;
mCurrent.setRotation(-rot> 180?rot/2:rot);
if(t<1.0)
{
handler.postDelayed(this,16);
}
}
});
}
private void startLocationUpdates() {
if(ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED &&
ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED )
{
return;
}
LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient,mLocationRequest, this);
}
@Override
public void onMapReady(GoogleMap googleMap) {
mMap = googleMap;
}
@Override
public void onLocationChanged(Location location) {
mLastLocation = location;
displayLocation();
}
// @Override
// public void onStatusChanged(String s, int i, Bundle bundle) {
//}
// @Override
// public void onProviderEnabled(String s) {
// }
// @Override
// public void onProviderDisabled(String s) {
//}
@Override
public void onConnected(@Nullable Bundle bundle) {
displayLocation();
startLocationUpdates();
}
@Override
public void onConnectionSuspended(int i) {
mGoogleApiClient.connect();
}
@Override
public void onConnectionFailed(@NonNull ConnectionResult connectionResult) {
}
}