com.google.firebase.database.DatabaseException：RecyclerViewを使用してjava.lang.String型のオブジェクトを型に変換できません

Question

私はこの問題を直面しています。私はこの記事database.DatabaseException: Can't convert object of type java.lang.String to typeを読んでいますが、どこが間違っていますか。私はあなたの助けがFirebaseで新しく必要です。

これは私のMainActivity.javaクラスです

public class MainActivity extends AppCompatActivity { 

    private Button but; 
    private DatabaseReference mRef; 
    private MyAdapter adapter; 
    public RecyclerView recyclerView; 

    public List<ModelClass> doctors; 
    public Context c; 
    private LinearLayoutManager linearLayoutManager; 

    public DatabaseReference mMovieRef ; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     doctors = new ArrayList<ModelClass>(); 

     recyclerView =(RecyclerView) findViewById(R.id.recyclerview); 

     linearLayoutManager = new LinearLayoutManager(this); 
     recyclerView.setLayoutManager(linearLayoutManager); 
     recyclerView.setHasFixedSize(true); 
     mRef = FirebaseDatabase.getInstance().getReference("Doctors"); 

     mRef.addChildEventListener(new ChildEventListener() { 
      @Override 
      public void onChildAdded(DataSnapshot dataSnapshot, String s) { 
       LoadData(dataSnapshot); 
      } 

      @Override 
      public void onChildChanged(DataSnapshot dataSnapshot, String s) { 
       LoadData(dataSnapshot); 
      } 

      public void onChildRemoved(DataSnapshot dataSnapshot) { } 
      public void onChildMoved(DataSnapshot dataSnapshot, String s) { } 
      public void onCancelled(DatabaseError databaseError) { } 
     }); 
    } 

    public void LoadData (DataSnapshot dataSnapshot){ 
     for(DataSnapshot ds :dataSnapshot.getChildren()){ 
      System.out.println(ds.getValue()); 
      ModelClass doc =ds.getValue(ModelClass.class); 

      doctors.add(doc); 

      adapter = new MyAdapter(MainActivity.this, doctors); 
      recyclerView.setAdapter(adapter); 
     } 
    } 
} 

これは私のAdapterクラスです

public class MyAdapter extends RecyclerView.Adapter<MyViewHolder> { 
    protected Context c; 
    List<ModelClass> doctors; 
    FirebaseStorage storage = FirebaseStorage.getInstance(); 

    StorageReference url =storage.getReferenceFromUrl("gs://askdoctor-546bf.appspot.com/"); 

    private List<ModelClass> itemList = null; 

    public MyAdapter(Context c, List<ModelClass> doctors) { 
     this.c = c; 
     this.doctors = doctors; 
    } 

    @Override 
    public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) { 

     View v = LayoutInflater.from(parent.getContext()).inflate(R.layout.item_activity,parent,false); 
     MyViewHolder holder = new MyViewHolder(v); 
     return holder; 
    } 

    @Override 
    public void onBindViewHolder(MyViewHolder holder, int position) { 
     final ModelClass feedItems = itemList.get(position); 

     holder.name.setText(doctors.get(position).getDoctorsName()); 
     holder.email_txt.setText(doctors.get(position).getEmail()); 
     // PicassoClient.downloadImage(c,doctors.get(position).getUrl(),holder.img); 
     //Download image using picasso library 
     Picasso.with(c).load(url+ feedItems.getPhoto()) 
       .error(R.mipmap.ic_launcher). 
       resize(120, 50) 
       .placeholder(R.mipmap.ic_launcher).into(holder.img); 
    } 

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

これは私のmodelクラスです

public class ModelClass { 
    private String DoctorsName; 
    private String Email; 
    private String Phone; 
    private String Photo; 

    public ModelClass() { 

     // empty default constructor, necessary for Firebase to be able to deserialize posts 
    } 

    public String getDoctorsName() { 
     return DoctorsName; 
    } 

    public void setDoctorsName(String doctorsName) { 
     DoctorsName = doctorsName; 
    } 

    public String getEmail() { 
     return Email; 
    } 

    public void setEmail(String email) { 
     Email = email; 
    } 

    public String getPhone() { 
     return Phone; 
    } 

    public void setPhone(String phone) { 
     Phone = phone; 
    } 

    public String getPhoto() { 
     return Photo; 
    } 

    public void setPhoto(String photo) { 
     Photo = photo; 
    } 
} 

これは私のFirebase database Console pictureです。

Answer 1

あなたは医師1と2の子にアクセスしようとしている、あなたの質問に、問題を再現し、完全な、最小限のコード+ JSON（テキストとして、なしスクリーンショット）を含めてください。このコード

  public void LoadData (DataSnapshot dataSnapshot) 

     {    

     System.out.println(ds.getValue()); 

     ModelClass doc =ds.getValue(ModelClass.class); 

     doctors.add(doc); 

     adapter = new MyAdapter(MainActivity.this, doctors); 
     recyclerView.setAdapter(adapter); 
    } 
}