小编And*_*ves的帖子

我正在尝试从Firebase数据库的dataSnapshot中检索更新的用户:

mRef.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(DataSnapshot dataSnapshot) {
            User atualizedUser = dataSnapshot.getValue(User.class);
            fName.setText(atualizedUser.getFirstName());
            lName.setText(atualizedUser.getLastName());
            profilePhoto.setProfileId(atualizedUser.getProfileId());
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {

        }
    });
}

但我得到以下错误:

com.google.firebase.database.DatabaseException: Class bqs.bomqueso.Model.User is missing a constructor with no arguments
                                                            at com.google.android.gms.internal.zzbtg$zza.zze(Unknown Source)
                                                            at com.google.android.gms.internal.zzbtg$zza.zzaH(Unknown Source)
                                                            at com.google.android.gms.internal.zzbtg.zze(Unknown Source)
                                                            at com.google.android.gms.internal.zzbtg.zzb(Unknown Source)
                                                            at com.google.android.gms.internal.zzbtg.zza(Unknown Source)
                                                            at com.google.firebase.database.DataSnapshot.getValue(Unknown Source)
                                                            at bqs.bomqueso.Activities.MainActivity$3.onDataChange(MainActivity.java:92)
                                                            at com.google.android.gms.internal.zzbpx.zza(Unknown Source)
                                                            at com.google.android.gms.internal.zzbqx.zzZS(Unknown Source)
                                                            at com.google.android.gms.internal.zzbra$1.run(Unknown Source)
                                                            at android.os.Handler.handleCallback(Handler.java:746)
                                                            at android.os.Handler.dispatchMessage(Handler.java:95)
                                                            at android.os.Looper.loop(Looper.java:148)
                                                            at android.app.ActivityThread.main(ActivityThread.java:5443)
                                                            at java.lang.reflect.Method.invoke(Native Method)
                                                            at     com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:728) …