Question

我正在android中创建一个方向性应用程序。为什么我必须从Android设备获取位置这里是我的代码当我运行此代码它给我这些行的例外

curlat = location.getLatitude();
curlng = location.getLongitude();

这是整个功能

public void newlocation(Context context) {
    locationManager = (LocationManager) getSystemService(Context.LOCATION_SERVICE);
    // Define the criteria how to select the location provider
    criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_COARSE); // default
    // user defines the criteria
    criteria.setCostAllowed(false);
    // get the best provider depending on the criteria
    provider = locationManager.getBestProvider(criteria, false);
    // the last known location of this provider

    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;
    }
    Location location = locationManager.getLastKnownLocation(provider);
    mylistener = new MyLocationListener();
    if (location != null) {
        mylistener.onLocationChanged(location);
    } else {
        // leads to the settings because there is no last known location
        Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
        startActivity(intent);
    }
    // location updates: at least 1 meter and 200millsecs change
    locationManager.requestLocationUpdates(provider, 200, 1, mylistener);
    // String a=""+location.getLatitude();
    // Toast.makeText(getApplicationContext(), a, 222).show();

    curlat = location.getLatitude();
    curlng = location.getLongitude();
    Log.d("************", "1111111111111111");
    new GetAddressTask(this).execute(location);

}

Answer 1

您正在获取位置的null对象，因此在访问lat和log之前进行空点检查

if(location!= null){
double latitude = location.getLatitude();
double longitude = location.getLongitude();}

ANdroid：java.lang.NullPointerException：尝试调用虚方法'double android.location.Location.getLatitude（）

1 个答案: