JsonMappingException：找不到适合类型的构造函数

Question

我正在使用 FirebaseUI 填充 RecyclerView

public class ViewRequestsFragment extends Fragment {
    private Firebase myUserFire,myListFire;
    protected RecyclerView.LayoutManager mLayoutManager;
    private FirebaseRecyclerAdapter<Request,RecyclerViewHolder> recyclerAdapter;
    public ViewRequestsFragment() {
        // Required empty public constructor
    }

    @Override
    public void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        String firbaseUrl= getArguments().getString(Constants.FIREBASE);
        myUserFire = new Firebase(firbaseUrl);
        myListFire = new Firebase(Constants.FIREBASE_REQUESTS);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        // Inflate the layout for this fragment

        View rootView= inflater.inflate(R.layout.fragment_view_requests, container, false);
        final RecyclerView recyclerView= (RecyclerView) rootView.findViewById(R.id.my_recycler_view);
        FragmentActivity fragmentActivity=getActivity();
        mLayoutManager = new LinearLayoutManager(fragmentActivity);
        recyclerView.setHasFixedSize(true);
        recyclerView.setLayoutManager(mLayoutManager);

        recyclerAdapter = new FirebaseRecyclerAdapter<Request, RecyclerViewHolder>(Request.class,R.layout.reques_list,RecyclerViewHolder.class, myListFire) {
            @Override
            protected void populateViewHolder(RecyclerViewHolder recyclerViewHolder, Request request, int i) {
                recyclerViewHolder.tv1.setText(request.getRiderId());
                recyclerViewHolder.tv2.setText(request.getDriverId());
            }


        };
        recyclerView.setAdapter(recyclerAdapter);
        return  rootView;
    }

    public static class RecyclerViewHolder extends RecyclerView.ViewHolder {
        TextView tv1, tv2;

        public RecyclerViewHolder(View itemView) {
            super(itemView);
            tv1 = (TextView) itemView.findViewById(R.id.list_title);
            tv2 = (TextView) itemView.findViewById(R.id.list_desc);
        }
    }

}

我收到以下错误

Caused by: com.fasterxml.jackson.databind.JsonMappingException: No suitable constructor found for type [simple type, class com.google.android.gms.maps.model.LatLng]: can not instantiate from JSON object (need to add/enable type information?)

这是我的 POJO class

public  class Request {       
    private String driverId;
    private LatLng latLng;

    public Request(){}

    public Request(String driverId) {           
        this.driverId = driverId;
    }   

    public Request(String driverId, LatLng latLng) {           
        this.driverId = driverId;
        this.latLng = latLng;
    } 
    public String getDriverId() {
        return driverId;
    }

    public void setDriverId(String driverId) {
        this.driverId = driverId;
    }

    public LatLng getLatLng() {
        return latLng;
    }

    public void setLatLng(LatLng latLng) {
        this.latLng = latLng;
    }
}

这是我正在尝试反序列化的JSON：

 {
  "driverId" : "null",
  "latLng" : {
    "latitude" : 38.421998333333335,
    "longitude" : -121.08400000000002
  }
}

我应该如何设计我的响应 class 以与 "latLng" 一起使用，我们将不胜感激。

Answer 1

您必须构建两个不同的模型：Request 和 LatLon。

要求：

public  class Request implements Serializable {       
    private String driverId;
    private LatLng latLng;

    public Request(){}

    public Request(String driverId) {           
        this.driverId = driverId;
    }   

    public Request(String driverId, LatLng latLng) {           
        this.driverId = driverId;
        this.latLng = latLng;
    } 
    public String getDriverId() {
        return driverId;
    }

    public void setDriverId(String driverId) {
        this.driverId = driverId;
    }

    public LatLng getLatLng() {
        return latLng;
    }

    public void setLatLng(LatLng latLng) {
        this.latLng = latLng;
    }
}

经纬度：

public  class LatLng implements Serializable{       
    private String lat;
    private String lon;

    public String getLat() {
        return lat;
    }

    public void setLat(String lat) {
        this.lat = lat;
    }

    public String getLon() {
        return lon;
    }

    public void setLon(String lon) {
        this.lon = lon;
    }
}

Answer 2

public  class LatLng {       
    public double latitude;
    public double longitude;

    public LatLng(){}
}

您可能还需要从 Request class

中删除其他构造函数

public  class Request {       
    public String driverId;
    public LatLng latLng;

    public Request(){}
}

当您将 class 变量声明为 public 时，您不必添加 getter。您可以简单地获取这些值，例如 request.driverId

JsonMappingException：找不到适合类型的构造函数

JsonMappingException: No suitable constructor found for type

android

firebase

firebase-realtime-database