我收到以下运行时错误: java.lang.NullPointerException:尝试在空对象引用上调用虚拟方法“double android.location.Location.getLatitude()”
import android.app.Activity;
import android.app.ProgressDialog;
import android.content.Context;
import android.content.pm.PackageManager;
import android.location.Location;
import android.location.LocationManager;
import android.os.AsyncTask;
import android.os.Build;
import android.os.Bundle;
import android.support.v4.content.ContextCompat;
import android.util.Log;
import android.widget.ListView;
import com.parse.ParseException;
import com.parse.ParseFile;
import com.parse.ParseGeoPoint;
import com.parse.ParseObject;
import com.parse.ParseQuery;
import java.util.ArrayList;
import java.util.List;
public class MainActivity extends Activity {
// Declare Variables
ListView listview;
List<ParseObject> ob;
ProgressDialog mProgressDialog;
ListViewAdapter adapter;
Context context;
private List<PlaceFilter> worldpopulationlist = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Get the view from listview_main.xml
setContentView(R.layout.activity_main);
// Execute RemoteDataTask AsyncTask
new RemoteDataTask().execute();
}
// RemoteDataTask AsyncTask
private class RemoteDataTask extends AsyncTask<Void, Void, Void> {
@Override
protected void onPreExecute() {
super.onPreExecute();
// Create a progressdialog
mProgressDialog = new ProgressDialog(MainActivity.this);
// Set progressdialog title
mProgressDialog.setTitle("Parse.com Custom ListView Tutorial");
// Set progressdialog message
mProgressDialog.setMessage("Loading...");
mProgressDialog.setIndeterminate(false);
// Show progressdialog
mProgressDialog.show();
}
LocationManager lm = (LocationManager)getSystemService(Context.LOCATION_SERVICE);
Location location = lm.getLastKnownLocation(LocationManager.GPS_PROVIDER);
double latitude = location.getLatitude();
double longitude = location.getLongitude();
这是 ParseQuery
try {
// Locate the class table named "Country" in Parse.com
ParseQuery<ParseObject> query = new ParseQuery<ParseObject>(
"geo_filters");
// Locate the column named "ranknum" in Parse.com and order list
// by ascending
ob=query.find();
for (ParseObject PlaceLocation : ob) {
// Locate images in flag column
ParseFile image = (ParseFile) PlaceLocation.get("FilterFile");
PlaceFilter map = new PlaceFilter();
ParseGeoPoint userLocation = new ParseGeoPoint(latitude, longitude);
query.whereNear("PlaceLocation", userLocation); //column as location
query.whereWithinKilometers("PlaceLocation", userLocation, 1);
map.setPlaceName((String) PlaceLocation.get("PlaceName"));
map.setFilterFile(image.getUrl());
worldpopulationlist.add(map);
}
} catch (ParseException e){
Log.e("Error",e.getMessage());
e.printStackTrace();
}
最佳答案
Runtime Error: java.lang.NullPointerException: Attempt to invoke virtual method 'double android.location.Location.getLatitude()' on a null object reference
位置为空,尚未初始化。
检查位置是否不为空:
if(location!= null){
double latitude = location.getLatitude();
double longitude = location.getLongitude();
}
此外,您应该将所有位置服务代码包装到 try and catch 中,并检查空指针引用和连接、GPS 提供商等。看看这里 BasicLocationSample .
关于java - 空对象引用上的 Location.getLatitude(),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/34498147/