Class android.location.Location 沒有定義無參構造函數

Question

我一直在嘗試簡單地將帶有兩個變量（一個字符串和一個位置）的 class 推送並讀取到 firebase，但我一直收到此錯誤。

**com.google.firebase.database.DatabaseException: Class android.location.Location does not define a no-argument constructor. If you are using ProGuard, make sure these constructors are not stripped.
                                                                            at com.google.android.gms.internal.zzeas.zze(Unknown Source:51)
                                                                            at com.google.android.gms.internal.zzear.zzb(Unknown Source:772)
                                                                            at com.google.android.gms.internal.zzear.zza(Unknown Source:312)
                                                                            at com.google.android.gms.internal.zzear.zzb(Unknown Source:0)
                                                                            at com.google.android.gms.internal.zzeas.zze(Unknown Source:209)
                                                                            at com.google.android.gms.internal.zzear.zzb(Unknown Source:772)
                                                                            at com.google.android.gms.internal.zzear.zza(Unknown Source:0)
                                                                            at com.google.firebase.database.DataSnapshot.getValue(Unknown Source:10)
                                                                            at com.example.vish.mcapp.Selection$2$1.onDataChange(Selection.java:85)
                                                                            at com.google.firebase.database.zzp.onDataChange(Unknown Source:7)
                                                                            at com.google.android.gms.internal.zzduz.zza(Unknown Source:13)
                                                                            at com.google.android.gms.internal.zzdwu.zzbvb(Unknown Source:2)
                                                                            at com.google.android.gms.internal.zzdxa.run(Unknown Source:65)
                                                                            at android.os.Handler.handleCallback(Handler.java:790)
                                                                            at android.os.Handler.dispatchMessage(Handler.java:99)
                                                                            at android.os.Looper.loop(Looper.java:164)
                                                                            at android.app.ActivityThread.main(ActivityThread.java:6494)
                                                                            at java.lang.reflect.Method.invoke(Native Method)
                                                                            at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:438)
                                                                            at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:807)**

class 其 object 我正在嘗試推送並從 firebase 讀取如下。

public class DeviceDetails {
   String nickname;
   Location location = new Location("Test");

    DeviceDetails()
     {
     }

     DeviceDetails(String nickname)
     {
     this.nickname = nickname;
     location.setLatitude(0.0);
     location.setLongitude(0.0);
     location.setTime(new Date().getTime());
     }

     DeviceDetails(String nickname, Location l)
     {
       this.nickname = nickname;
       location=l;
}

}

將數據推送到 Firebase 工作正常。 但是如果不遇到上面的錯誤，我就無法閱讀它。

我為寫入 firebase 編寫的代碼是：-

register.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            if(TextUtils.isEmpty(nickname.getText().toString()))
            {
                Toast.makeText(Selection.this, "Nickname can't be empty", Toast.LENGTH_SHORT).show();
                return;
            }
            else
            {
                Location loc = new Location("");
                loc.setLatitude(19.0);
                loc.setLongitude(29.5);
                loc.setTime(new Date().getTime());
                DeviceDetails newDevice = new DeviceDetails(nickname.getText().toString(), loc);
                mDatabase.child("Phones").child(nickname.getText().toString().trim().replaceAll("\\s","")).setValue(newDevice);
            }


        }
    });

我為閱讀 Firebase 而編寫的代碼我認為是罪魁禍首是：-

retrieve.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View view) {

            DatabaseReference database = FirebaseDatabase.getInstance().getReference();
            DatabaseReference myRef = database.child("Phones");
            myRef.child(nickToRetrieve.getText().toString().trim().replaceAll("\\s", "")).addListenerForSingleValueEvent(new ValueEventListener() {
                @Override
                public void onDataChange(DataSnapshot dataSnapshot) {
                    DeviceDetails dev = dataSnapshot.getValue(DeviceDetails.class);
                    double latitude = dev.location.getLatitude();
                    double longitude = dev.location.getLongitude();
                    String loc = "Latitude - " + latitude + " Longitude - " + longitude;
                    Toast.makeText(Selection.this, loc, Toast.LENGTH_LONG).show();
                }

                @Override
                public void onCancelled(DatabaseError databaseError) {

                }
            });

任何幫助是極大的贊賞。

Answer 1

當Firebase Realtime Database SDK反序列化來自數據庫的對象時，它要求所有使用中的對象都具有可用於實例化該對象的公共無參數構造函數。 通過使用setter方法或直接訪問公共成員來設置對象中的字段。

Android的Location對象沒有公共的無參數構造函數，因此SDK並不真正知道如何創建其實例。 實際上，大多數序列化庫將具有相同的要求。 因此，不要使用Android的Location對象，而要使用自己的對象，並根據需要將數據復制進出。

Answer 2

我只是自己做了一個 model -

public class RequestLocation implements Parcelable {
    private  double lat;
    private double lon;

    protected RequestLocation(Parcel in) {
        lat = in.readDouble();
        lon = in.readDouble();
    }

    @Override
    public void writeToParcel(Parcel dest, int flags) {
        dest.writeDouble(lat);
        dest.writeDouble(lon);
    }

    @Override
    public int describeContents() {
        return 0;
    }

    public static final Creator<RequestLocation> CREATOR = new Creator<>() {
        @Override
        public RequestLocation createFromParcel(Parcel in) {
            return new RequestLocation(in);
        }

        @Override
        public RequestLocation[] newArray(int size) {
            return new RequestLocation[size];
        }
    };

    public double getLat() {
        return lat;
    }

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

    public double getLon() {
        return lon;
    }

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

    public RequestLocation(double lat, double lon) {
        this.lat = lat;
        this.lon = lon;
    }

   public RequestLocation(){
      
    }

}

並發布它而不是框架的位置 object。