java - 无法将本地值分配给全局值
问题描述
我只是java/android的初学者。我试图将位置纬度和经度传递给火力基地。因此,我敬酒以查看它显示的值 0.0。我将 lat 和 long 值从 client.getlastlocation 传递到 lat 和 lon 的全局值,但它显示默认值 0.0,为什么会这样?
public class shopaction extends Fragment implements CompoundButton.OnCheckedChangeListener{
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
Location location;
GoogleApiClient googleApiClient;
FusedLocationProviderClient client;
private String mParam1;
private String mParam2;
String s;
Switch action;
public double lat,lon;
private OnFragmentInteractionListener mListener;
public shopaction() {
}
public static shopaction newInstance(String param1, String param2) {
shopaction fragment = new shopaction();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_shopaction, container, false);
}
@Override
public void onViewCreated(@NonNull View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
action = (Switch) view.findViewById(R.id.action);
action.setOnCheckedChangeListener(this);
client = LocationServices.getFusedLocationProviderClient(getActivity());
Button button=(Button)view.findViewById(R.id.button);
button.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
if (ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_FINE_LOCATION) != PackageManager.PERMISSION_GRANTED && ActivityCompat.checkSelfPermission(getActivity(), Manifest.permission.ACCESS_COARSE_LOCATION) != PackageManager.PERMISSION_GRANTED) {
ActivityCompat.requestPermissions(getActivity(),new String[]{Manifest.permission.ACCESS_FINE_LOCATION},1);
}
client.getLastLocation().addOnSuccessListener(getActivity(), new OnSuccessListener<Location>() {
@Override
public void onSuccess(Location location) {
lat=location.getLatitude();
lon=location.getLongitude();
}
});
}
});
client.getLastLocation().addOnSuccessListener(getActivity(), new OnSuccessListener<Location>() {
@Override
public void onSuccess(Location location) {
lat=location.getLatitude();
lon=location.getLongitude();
}
});
Toast.makeText(getActivity(),lat+"",Toast.LENGTH_LONG).show();
FirebaseDatabase firebaseDatabase=FirebaseDatabase.getInstance();
DatabaseReference databaseReference=firebaseDatabase.getReference();
databaseReference.child("shop").child("location").setValue(lat);
}
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
if (context instanceof OnFragmentInteractionListener) {
mListener = (OnFragmentInteractionListener) context;
} else {
throw new RuntimeException(context.toString()
+ " must implement OnFragmentInteractionListener");
}
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
@Override
public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {
if(action.isChecked())
{
Toast.makeText(getActivity(),"Your shop is open",Toast.LENGTH_LONG).show();
action.setText("open");
s="open";
}
else
{
Toast.makeText(getActivity(),"Your shop is closed",Toast.LENGTH_LONG).show();
action.setText("close");
s="close";
}
}
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
}
解决方案
问题是getLastLocation()
返回 aTask
然后异步操作。在实际调用成功侦听器回调之前,位置数据不可用。同时,您的代码继续Toast
使用当前(默认)值 0 来显示lat
和lon
。
解决此问题的一种方法是让您的成功侦听器回调显示 toast,而不是您的主代码。所以代替这个:
client.getLastLocation().addOnSuccessListener(getActivity(), new OnSuccessListener<Location>() {
@Override
public void onSuccess(Location location) {
lat=location.getLatitude();
lon=location.getLongitude();
}
});
Toast.makeText(getActivity(),lat+"",Toast.LENGTH_LONG).show();
// Firebase update code that depends on location data
用这个:
client.getLastLocation().addOnSuccessListener(getActivity(), new OnSuccessListener<Location>() {
@Override
public void onSuccess(Location location) {
lat=location.getLatitude();
lon=location.getLongitude();
Toast.makeText(getActivity(),lat+"",Toast.LENGTH_LONG).show();
// Firebase update code that depends on location data
}
});
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