android - 尝试输入 onDataChange Firebase Android 时应用程序崩溃

Question

我想在cardview中向我展示所有来自firebase数据库的用户，这些用户在recyclerview中，但在调试器中在UserActivity的第60行显示错误。我在我的数据库中放了一个截图：

用户片段：

public class UsersFragment extends Fragment {
    private RecyclerView recyclerView;
    private UserAdapter userAdapter;
    private List<User> mUsers;


    @Override
    public View onCreateView (LayoutInflater inflater, ViewGroup container,
                              Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View view= inflater.inflate ( R.layout.fragment_users3, container, false );
recyclerView=view.findViewById (R.id.recycler_view  );

recyclerView.setLayoutManager ( new LinearLayoutManager ( getContext () ) );
mUsers=new ArrayList<> (  );
readUsers();

        return view;
    }

    private void readUsers () {
        final FirebaseUser firebaseUser= FirebaseAuth.getInstance ().getCurrentUser ();
        DatabaseReference referenc= FirebaseDatabase.getInstance ().getReference ("users");

        referenc.addValueEventListener ( new ValueEventListener () {
            @Override
            public void onDataChange (@NonNull DataSnapshot dataSnapshot) {
                mUsers.clear ();
                for(DataSnapshot snapshot:dataSnapshot.getChildren ()){
                    User user=snapshot.getValue (User.class);
                    assert user!=null;
                    assert firebaseUser!=null;
                    if(!firebaseUser.getUid ().equals ( user.getUid () )){
                        mUsers.add ( user );

                    }
                }
                userAdapter=new UserAdapter ( getContext (),mUsers );
                recyclerView.setAdapter ( userAdapter );
            }

            @Override
            public void onCancelled (@NonNull DatabaseError databaseError) {

            }
        } );
    }


}

UserAdapter.In 我使用了 User 类：

public class UserAdapter extends RecyclerView.Adapter<UserAdapter.ViewHolder> {
    private Context mContext;
    private List<User> mUsers;
    public UserAdapter(Context mContext,List<User> mUsers){
        this.mUsers=mUsers;
        this.mContext=mContext;
    }

    @NonNull
    @Override
    public ViewHolder onCreateViewHolder (@NonNull ViewGroup parent, int viewType) {
        View view= LayoutInflater.from ( mContext ).inflate ( R.layout.users_template ,parent,false);

        return new UserAdapter.ViewHolder ( view );
    }

    @Override
    public void onBindViewHolder (@NonNull ViewHolder holder, int position) {
User user=mUsers.get ( position );
holder.username.setText ( user.getFirstName () );

    }

    @Override
    public int getItemCount () {
        return mUsers.size ();
    }

    public class ViewHolder extends RecyclerView.ViewHolder{

        public TextView username;

        public ViewHolder(View itemView){
            super(itemView);
            username=itemView.findViewById ( R.id.username1 );
        }

    }
}

存储 FirstName 的用户：

public class User {
   public String firstName;
    public String secondName;
    public String uid;
    public String email;
    public User(){

    }



    public User (String firstName, String secondName, String uid, String email) {
        this.firstName = firstName;
        this.secondName = secondName;
        this.uid=uid;
        this.email=email;
    }

    public User (String firstname, String secondname) {
    }
@PropertyName ( "FirsName" )
    public String getFirstName () {
        return firstName;
    }
    @PropertyName ("SecondName" )
    public String getSecondName () {
        return secondName;
    }
    @PropertyName ( "Uid" )
    public String getUid () {
        return uid;
    }
    @PropertyName ( "E-mail" )
    public String getEmail () {
        return email;
    }
    @PropertyName ( "FirsName" )
    public void setFirstName (String firstName) {
        this.firstName = firstName;
    }
    @PropertyName ( "SecondName" )
    public void setSecondName (String secondName) {
        this.secondName = secondName;
    }
    @PropertyName ( "Uid" )
    public void setUid (String uid) {
        this.uid = uid;
    }
    @PropertyName ( "E-mail" )
    public void setEmail (String email) {
        this.email = email;
    }
}

我的数据库的规则是：

{
  "rules": {
    ".read": "true",
      ".write":"true",
    "users":{
    "$user_id":{
       ".read": "auth.uid === $user_id",
       ".write": "auth.uid === $user_id"

    }
  }
}
}

在调试模式下，它向我显示：

E/AndroidRuntime: FATAL EXCEPTION: main
    Process: com.example.sportsbuddy, PID: 662
    com.google.firebase.database.DatabaseException: Found two getters or fields with conflicting case sensitivity for property: secondname
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.addProperty(com.google.firebase:firebase-database@@17.0.0:540)
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.<init>(com.google.firebase:firebase-database@@17.0.0:471)
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.loadOrCreateBeanMapperForClass(com.google.firebase:firebase-database@@17.0.0:312)
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(com.google.firebase:firebase-database@@17.0.0:413)
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(com.google.firebase:firebase-database@@17.0.0:214)
        at com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertToCustomClass(com.google.firebase:firebase-database@@17.0.0:79)
        at com.google.firebase.database.DataSnapshot.getValue(com.google.firebase:firebase-database@@17.0.0:212)
        at com.example.sportsbuddy.Fragments.UsersFragment$1.onDataChange(UsersFragment.java:60)
        at com.google.firebase.database.core.ValueEventRegistration.fireEvent(com.google.firebase:firebase-database@@17.0.0:75)
        at com.google.firebase.database.core.view.DataEvent.fire(com.google.firebase:firebase-database@@17.0.0:63)
        at com.google.firebase.database.core.view.EventRaiser$1.run(com.google.firebase:firebase-database@@17.0.0:55)
        at android.os.Handler.handleCallback(Handler.java:873)
        at android.os.Handler.dispatchMessage(Handler.java:99)
        at android.os.Looper.loop(Looper.java:214)
        at android.app.ActivityThread.main(ActivityThread.java:6986)
        at java.lang.reflect.Method.invoke(Native Method)
        at com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:493)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1445)

主要错误出现在 UsersFragment 中的 onDataChange 上。

我希望向我展示我在数据库中拥有的所有用户。

标签： androidfirebasefirebase-realtime-database

Answer 1

你的错误说：

Found two getters or fields with conflicting case sensitivity for property: secondname

要了解此错误的含义，您需要了解 Firebase 如何对从数据库接收的数据进行序列化和反序列化。

Firebase 使用字段名称以及 getter 和 setter 来序列化和反序列化对象，这意味着，每当您从数据库接收 JSON 对象时，firebase 都会将这些键值与您的 getter/setter 以及 POJO 类中的字段进行映射。

要删除此错误，您必须更改字段名称，即

public String secondName;

与数据库中的内容不同，或者，您需要更改 getter 和 setter 函数名称。错误是因为 firebase 两次看到该属性，一次在您的字段中，第二次在您的 getter/setter 中。

另外，尝试将您的变量设为私有。它可能会有所帮助。另外，如何将数据库中的“电子邮件”更改为简单的“电子邮件”？