getLatitude 上的空指针异常

Posted 2023-02-23

【中文标题】getLatitude 上的空指针异常

【英文标题】：Null Pointer Exception on getLatitude

【发布时间】：2016-02-17 10:31:23

【问题描述】：

空对象引用上的'double android.location.Location.getLatitude()'

 return new ParseGeoPoint(loc.getLatitude(), loc.getLongitude());

并使用 ParseGeoQuery

query.whereWithinKilometers("GeoArea", geoPointFromLocation(myLoc), radius);

这是初始化位置的onCreate方法

   // Create a new global location parameters object
        locationRequest = LocationRequest.create();

        // Set the update interval
        locationRequest.setInterval(UPDATE_INTERVAL_IN_MILLISECONDS);

        // Use high accuracy
        locationRequest.setPriority(LocationRequest.PRIORITY_HIGH_ACCURACY);

        // Set the interval ceiling to one minute
        locationRequest.setFastestInterval(FAST_INTERVAL_CEILING_IN_MILLISECONDS);

        // Create a new location client, using the enclosing class to handle callbacks.
        locationClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();

这是我对 GeoLocation 的 ParseQuery

@Override
    public void onStart() 
        super.onStart();

        // Connect to the location services client
        locationClient.connect();
    
     FiltersQueryAdapter mainAdapter = new FiltersQueryAdapter(this, PhotoFiltersAdapter.class
                , new ParseRecyclerQueryAdapter.QueryFactory() 
            public ParseQuery create() 
                Location myLoc = (currentLocation == null) ? lastLocation : currentLocation;
                ParseQuery query = ParseQuery.getQuery("PlaceFilters");
                //query.include("user");
                query.orderByAscending("GeoArea");
                query.whereWithinKilometers("GeoArea", geoPointFromLocation(myLoc), radius);
                query.setLimit(6);
                return query;
            
        );

     @Override
        protected void onResume() 
            super.onResume();
            cameraView.onResume();

            // Get the latest search distance preference
            radius = InstaMaterialApplication.getSearchDistance();
            // Checks the last saved location to show cached data if it's available
            if (lastLocation != null) 
                // If the search distance preference has been changed, move
                // map to new bounds.
                if (lastRadius != radius) 
                    // Save the current radius
                    lastRadius = radius;
                    doListQuery();
                
            
        

        public void onConnected(Bundle bundle) 
                if (InstaMaterialApplication.APPDEBUG) 
                    Log.d("Location Connected", InstaMaterialApplication.APPTAG);
                
                currentLocation = getLocation();
                startPeriodicUpdates();
            

          public void onLocationChanged(Location location) 
                currentLocation = location;
                if (lastLocation != null
                            && geoPointFromLocation(location)
                            .distanceInKilometersTo(geoPointFromLocation(lastLocation)) < 0.01)
                
                    // If the location hasn't changed by more than 10 meters, ignore it.
                    return;
                
                lastLocation = location;

                if (!hasSetUpInitialLocation) 
                    hasSetUpInitialLocation = true;
                
                // Update map radius indicator
                doListQuery();
            

            /*
           * In response to a request to start updates, send a request to Location Services
           */
            private void startPeriodicUpdates() 
                if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) 
                    // TODO: Consider calling
                    //    ActivityCompat#requestPermissions
                    // here to request the missing permissions, and then overriding
                    //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                    //                                          int[] grantResults)
                    // to handle the case where the user grants the permission. See the documentation
                    // for ActivityCompat#requestPermissions for more details.
                    return;
                
                LocationServices.FusedLocationApi.requestLocationUpdates(
                        locationClient, locationRequest, this);
            

            /*
             * In response to a request to stop updates, send a request to Location Services
             */
            private void stopPeriodicUpdates() 
                locationClient.disconnect();
            

            /*
           * Get the current location
           */
            private Location getLocation() 
                // If Google Play Services is available
                if (servicesConnected()) 
                    // Get the current location
                    if (ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(this, Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) 
                        // TODO: Consider calling
                        //    ActivityCompat#requestPermissions
                        // here to request the missing permissions, and then overriding
                        //   public void onRequestPermissionsResult(int requestCode, String[] permissions,
                        //                                          int[] grantResults)
                        // to handle the case where the user grants the permission. See the documentation
                        // for ActivityCompat#requestPermissions for more details.
                    
                    return LocationServices.FusedLocationApi.getLastLocation(locationClient);
                 else 
                    return null;
                
            

            /*
           * Set up a query to update the list view
           */
            private void doListQuery() 
                Location myLoc = (currentLocation == null) ? lastLocation : currentLocation;
                // If location info is available, load the data
            

            /*
           * Helper method to get the Parse GEO point representation of a location
           */
            private ParseGeoPoint geoPointFromLocation(Location loc) 
                return new ParseGeoPoint(loc.getLatitude(), loc.getLongitude());
            

我的清单访问 Google Play 服务和位置的权限

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION" />
    <uses-permission android:name="android.permission.INTERNET" />
    <uses-permission android:name="android.permission.CAMERA" />
    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />
    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
    <uses-permission android:name="com.google.android.providers.gsf.permission.READ_GSERVICES" />

【问题讨论】：

loc的值必须为null（它必须没有任何值）

除了 ParseGeoPoint GeoPointfromLocation 之外，我没有在其他地方将其称为 getLatitude

@saeed 我应该添加这个双纬度 = location.getLatitude();低于 lastLocation = 位置

@saeed 我在 loc.getLatitude 上获得 Null 并获得 loc.getLongitude，因为我已将其发布在我的帖子顶部。您还可以在 ParseGeoQuery 部分找到它吗？它已发布在底部

What is a Null Pointer Exception, and how do I fix it?的可能重复

【参考方案1】：

在您的清单中添加以下另一个权限

<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION"/>

我知道您正在使用 ACCESS_FINE_LOCATION，但是如果您丢失 GPS 信号并尝试获得更长的纬度怎么办。在这种情况下，您将获得空数据。为了避免这种情况，最好有另一种选择从网络提供商那里获得位置，尽管它可能不准确。

确保在您的客户端构建器之后将您的 googleApiClient 与此调用连接起来。

// Create a new location client, using the enclosing class to handle callbacks.
        locationClient = new GoogleApiClient.Builder(this)
                .addApi(LocationServices.API)
                .addConnectionCallbacks(this)
                .addOnConnectionFailedListener(this)
                .build();

locationClient.connect();

【讨论】：

仍然返回空指针异常

检查您的客户端是否已连接。如果没有，请致电 locationClient.connect();

应该将 locationCLient.connect() 传递到哪里？

已更新答案 - 在 onCreate 中的客户端构建器之后

我在 @Override onStart() 中有 locationClient.connect()