从 android studio Firebase 提取数据时出现以下错误

Question

我无法理解这个问题。试图从实时数据库或 code.firebasteki 中提取信息到屏幕时出现这样的错误，这是什么问题？

本书

public class Book {
private String isim;
private String soyad;
private String numara;

public Book() {
}

public Book(String isim, String soyad, String numara) {
    this.isim = isim;
    this.soyad = soyad;
    this.numara = numara;
}

public String getIsim() {
    return isim;
}

public void setIsim(String isim) {
    this.isim = isim;
}

public String getSoyad() {
    return soyad;
}

public void setSoyad(String soyad) {
    this.soyad = soyad;
}

public String getNumara() {
    return numara;
}

public void setNumara(String numara) {
    this.numara = numara;
}

主要活动

public class MainActivity extends AppCompatActivity {
private RecyclerView mrecyclerView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    mrecyclerView=(RecyclerView) findViewById(R.id.recyclerview_books);
    new FirebaseDatabaseHelper().readBooks(new FirebaseDatabaseHelper.DataStatus() {
        @Override
        public void DataIsLoaded(List<Book> books, List<String> keys) {
            new RecyclerView_Config().setConfig(mrecyclerView,MainActivity.this,books,keys);
        }

        @Override
        public void DataIsInserted() {

        }

        @Override
        public void DataIsUpdated() {

        }

        @Override
        public void DataIsDeleted() {

        }
    });
}

RecyclerView_Config

public class RecyclerView_Config {
private Context mContext;
private BookAdapter mbookAdapter;
public void setConfig(RecyclerView recyclerView,Context context,List<Book> books,List<String> 
 keys){
    mContext=context;
    mbookAdapter=new BookAdapter(books,keys);
    recyclerView.setLayoutManager(new LinearLayoutManager(context));
    recyclerView.setAdapter(mbookAdapter);
}


  class BookItemView extends RecyclerView.ViewHolder{
    private TextView misim;
    private TextView msoyad;
    private TextView mnumara;
    private String key;

    public BookItemView(ViewGroup parent){
        super(LayoutInflater.from(mContext).
                inflate(R.layout.book_list_item,parent,false));

        misim=(TextView) itemView.findViewById(R.id.isim_textView);
        msoyad=(TextView) itemView.findViewById(R.id.soyad_textView);
        mnumara=(TextView) itemView.findViewById(R.id.numara_textView);


    }
    public void bind(Book book,String key){
        misim.setText(book.getIsim());
        msoyad.setText(book.getSoyad());
        mnumara.setText(book.getNumara());
        this.key=key;
    }
}
class BookAdapter extends RecyclerView.Adapter<BookItemView>{
private List<Book> mbookList;
private List<String> mkeys;

    public BookAdapter(List<Book> mbookList, List<String> mkeys) {
        this.mbookList = mbookList;
        this.mkeys = mkeys;
    }

    @NonNull
    @Override
    public BookItemView onCreateViewHolder(@NonNull ViewGroup parent, int viewType) {
        return new BookItemView(parent);
    }

    @Override
    public void onBindViewHolder(@NonNull BookItemView holder, int position) {
        holder.bind(mbookList.get(position),mkeys.get(position));
    }

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

FirebaseDatabaseHelper

public class FirebaseDatabaseHelper {
private FirebaseDatabase mDatabase;
private DatabaseReference mReferenceBook;
private List<Book> books=new ArrayList<>();

public interface DataStatus{
    void DataIsLoaded(List<Book> books,List<String> keys);
    void DataIsInserted();
    void DataIsUpdated();
    void DataIsDeleted();
}

public FirebaseDatabaseHelper() {
    mDatabase=FirebaseDatabase.getInstance();
    mReferenceBook=mDatabase.getReference("Kullanicilar");
}
public void readBooks(final DataStatus dataStatus){
    mReferenceBook.addValueEventListener(new ValueEventListener() {
        @Override
        public void onDataChange(@NonNull DataSnapshot snapshot) {
            books.clear();
            List<String> keys=new ArrayList<>();
            for(DataSnapshot keyNode:snapshot.getChildren()){
                keys.add(keyNode.getKey());
                Book book=keyNode.getValue(Book.class);
                books.add(book);
            }
            dataStatus.DataIsLoaded(books,keys);
        }

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

        }
    });
    }

firebase

E/AndroidRuntime：致命异常：main 进程：com.example.phonebook，PID：14998 com.google.firebase.database.DatabaseException: 无法将类型 java.lang.Long 的值转换为字符串在 com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertString(CustomClassMapper.java:426) 在 com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(CustomClassMapper.java:217) 在 com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToType(CustomClassMapper.java:179) 在 com.google.firebase.database.core.utilities.encoding.CustomClassMapper.access100 美元（CustomClassMapper.java:48）在 com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.deserialize(CustomClassMapper.java:593) 在 com.google.firebase.database.core.utilities.encoding.CustomClassMapper$BeanMapper.deserialize(CustomClassMapper.java:563) 在 com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertBean(CustomClassMapper.java:433) 在 com.google.firebase.database.core.utilities.encoding.CustomClassMapper.deserializeToClass(CustomClassMapper.java:232) 在 com.google.firebase.database.core.utilities.encoding.CustomClassMapper.convertToCustomClass(CustomClassMapper.java:80) 在 com.google.firebase.database.DataSnapshot.getValue(DataSnapshot.java:203) 在 com.example.phonebook.FirebaseDatabaseHelper$1.onDataChange(FirebaseDatabaseHelper.java:38) 在 com.google.firebase.database.core.ValueEventRegistration.fireEvent(ValueEventRegistration.java:75) 在 com.google.firebase.database.core.view.DataEvent.fire(DataEvent.java:63) 在 com.google.firebase.database.core.view.EventRaiser$1.run(EventRaiser.java:55) 在 android.os.Handler.handleCallback(Handler.java:883) 在 android.os.Handler.dispatchMessage(Handler.java:100) 在 android.os.Looper.loop(Looper.java:214) 在 android.app.ActivityThread.main(ActivityThread.java:7356) 在 java.lang.reflect.Method.invoke（本机方法）在 com.android.internal.os.RuntimeInit$MethodAndArgsCaller.run(RuntimeInit.java:492) 在 com.android.internal.os.ZygoteInit.main(ZygoteInit.java:930)

Answer 1

名为 numara 的字段作为字符串存在于您的 Book class 中，而在您的数据库中包含一个数字。这就是您收到该错误的原因。要解决这个问题，只需像这样更改 class 的声明：

public class Book {
    private String isim;
    private String soyad;
           //
    private long numara;

    public Book() {
    }

                                          //
    public Book(String isim, String soyad, long numara) {
        this.isim = isim;
        this.soyad = soyad;
        this.numara = numara;
    }

    public String getIsim() {
        return isim;
    }

    public void setIsim(String isim) {
        this.isim = isim;
    }

    public String getSoyad() {
        return soyad;
    }

    public void setSoyad(String soyad) {
        this.soyad = soyad;
    }

          //
    public long getNumara() {
        return numara;
    }

                         //
    public void setNumara(long numara) {
        this.numara = numara;
    }
}

从 android studio Firebase 提取数据时出现以下错误

I got the following error while pulling data from android studio Firebase

java

android

firebase

google-cloud-platform

firebase-realtime-database