java - 带类映射器 : No setter/field for class

标签 java android firebase android-fragments firebase-realtime-database

我只是尝试将 Firebase 数据库中的数据填充到我的 recyclerview 中。我的 recyclerview 显示完美，但适配器不会将值设置为 recyclerview textview 中的文本，它只说“在类 com.example.barry.starcity.StreetClass 上找不到 -L57t4-97c3dLZjA_yXC 的 setter /字段”。这让我觉得我的 setter 没有正确制作，但是 Android Studio 自动生成了。我不知道我在这里缺少什么。如有任何帮助，我们将不胜感激。

节点对象

  class StreetClass {

private String id;
private String semail;
private String sname;
private String stype;
private String sdetail;
private String slocation;
private String sdate;
private String imgurl;

public StreetClass(){

}

public String getImgurl() {
    return imgurl;
}

public void setImgurl(String imgurl) {
    this.imgurl = imgurl;
}

public String getId() {return id;}

public void setId(String id) {
    this.id = id;
}

public String getEmail() {
    return semail;
}

public void setEmail(String email) {
    this.semail = email;
}

public String getName() {
    return sname;
}

public void setName(String name) {
    this.sname = name;
}

public String getType() {
    return stype;
}

public void setType(String type) {
    this.stype = type;
}

public String getDetail() {
    return sdetail;
}

public void setDetail(String detail) {
    this.sdetail = detail;
}

public String getLocation() {
    return slocation;
}

public void setLocation(String location) {
    this.slocation = location;
}

public String getDate() {
    return sdate;
}

public void setDate(String date) {
    this.sdate = date;
}
}

RecyclerViewAdapter

 public class RecyclerViewAdapter extends 
 RecyclerView.Adapter<RecyclerViewAdapter.ViewHolder> {

Context context;
List<StreetClass>listdata ;

public RecyclerViewAdapter(Context context, List<StreetClass> list) {

    this.listdata = list;
    this.context = context;
}

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

    View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.recyclerview_items, parent, false);
    ViewHolder viewHolder = new ViewHolder(view);
    return viewHolder;
}

@Override
public void onBindViewHolder(ViewHolder holder, int position) {

    StreetClass AllDetails = listdata.get(position);

    holder.NameTextView.setText(AllDetails.getName());
    holder.DetailTextView.setText(AllDetails.getDetail());
    holder.EmailTextView.setText(AllDetails.getEmail());
    holder.DateTextView.setText(AllDetails.getDate());
    holder.LocationTextView.setText(AllDetails.getLocation());
    holder.TypeTextView.setText(AllDetails.getType());
}

@Override
public int getItemCount() {

    return listdata.size();
}

class ViewHolder extends RecyclerView.ViewHolder {

    public TextView NameTextView;
    public TextView DetailTextView;
    public TextView EmailTextView;
    public TextView DateTextView;
    public TextView LocationTextView;
    public TextView TypeTextView;
    /*public ImageView ImageTextView;*/

    public ViewHolder(View itemView) {

        super(itemView);
        NameTextView = itemView.findViewById(R.id.ShowNameTextView);
        DetailTextView = itemView.findViewById(R.id.ShowDetailTextView);
        EmailTextView = itemView.findViewById(R.id.ShowEmailTextView);
        DateTextView = itemView.findViewById(R.id.ShowDateTextView);
        LocationTextView = itemView.findViewById(R.id.ShowLocationTextView);
        TypeTextView = itemView.findViewById(R.id.ShowTypeTextView)

    }
  }
 }

主要 Activity 

  public class StatusFragment extends Fragment {

DatabaseReference databaseStatus;
ProgressDialog progressDialog;
List<StreetClass> list = new ArrayList<StreetClass>();
RecyclerView recyclerView;
RecyclerView.Adapter adapter;

public StatusFragment() {
    // Required empty public constructor
}

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);

}

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

    // Inflate the layout for this fragment
    View rootView = inflater.inflate(R.layout.fragment_status, container, false);

    recyclerView = rootView.findViewById(R.id.recyclerView);
    recyclerView.setHasFixedSize(true);
    recyclerView.setLayoutManager(new LinearLayoutManager(getContext().getApplicationContext()));

    progressDialog = new ProgressDialog(getActivity());
    progressDialog.setMessage("Loading Data from Firebase Database");
    progressDialog.show();

    databaseStatus = FirebaseDatabase.getInstance().getReference().child("Street Problems");
    databaseStatus.addValueEventListener(new ValueEventListener() {

        @Override
        public void onDataChange(DataSnapshot snapshot) {

            for (DataSnapshot dataSnapshot : snapshot.getChildren()) {

                StreetClass streetClass = dataSnapshot.getValue(StreetClass.class);

                list.add(streetClass);

            }
            adapter = new RecyclerViewAdapter(getContext().getApplicationContext(), list);
            recyclerView.setAdapter(adapter);
            adapter.notifyDataSetChanged();
            progressDialog.dismiss();
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
            progressDialog.dismiss();
        }
    });

    return  rootView;
}

项目的布局: 

    <android.support.v7.widget.CardView
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:card_view="http://schemas.android.com/apk/res-auto"
    android:id="@+id/cardview1"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    card_view:cardElevation="5dp"
    card_view:contentPadding="5dp"
    card_view:cardCornerRadius="5dp"
    card_view:cardMaxElevation="5dp">

    <RelativeLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#ECEFF1"
        android:padding="10dp">

        <TextView
            android:id="@+id/Name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="Student Name: "
            android:textColor="#000"
            android:textSize="10dp" />

        <TextView
            android:id="@+id/Detail"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="Detail: "
            android:textColor="#000"
            android:textSize="10dp"
            android:layout_below="@+id/Name"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" />

        <TextView
            android:id="@+id/Email"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="Email: "
            android:textColor="#000"
            android:textSize="10dp"
            android:layout_below="@+id/Detail"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" />

        <TextView
            android:id="@+id/Date"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="Date: "
            android:textColor="#000"
            android:textSize="10dp"
            android:layout_below="@+id/Email"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" />

        <TextView
            android:id="@+id/Location"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="Location "
            android:textColor="#000"
            android:textSize="10dp"
            android:layout_below="@+id/Date"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" />

      <!--  <TextView
            android:id="@+id/Image"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_below="@+id/Type"
            android:layout_toStartOf="@+id/ShowNameTextView"
            android:text="Uploaded image: "
            android:textColor="#000"
            android:textSize="10dp" />-->

        <TextView
            android:id="@+id/Type"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="Type: "
            android:textColor="#000"
            android:textSize="10dp"
            android:layout_below="@+id/Location"
            android:layout_alignParentLeft="true"
            android:layout_alignParentStart="true" />



        <TextView
            android:id="@+id/ShowNameTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:gravity="center"
            android:text="Show Student Name"
            android:textColor="#000"
            android:textSize="10dp"
            android:layout_alignParentTop="true"
            android:layout_toRightOf="@+id/Name"
            android:layout_toEndOf="@+id/Name"
            android:layout_marginLeft="19dp"
            android:layout_marginStart="19dp" />


        <TextView
            android:id="@+id/ShowDetailTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignStart="@+id/ShowNameTextView"
            android:layout_below="@+id/ShowNameTextView"
            android:gravity="center"
            android:text="Show Detail"
            android:textColor="#000"
            android:textSize="10dp" />

        <TextView
            android:id="@+id/ShowEmailTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignStart="@+id/ShowNameTextView"
            android:layout_below="@+id/ShowDetailTextView"
            android:gravity="center"
            android:text="Show Email"
            android:textColor="#000"
            android:textSize="10dp" />

        <TextView
            android:id="@+id/ShowDateTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignStart="@+id/ShowEmailTextView"
            android:layout_below="@+id/ShowEmailTextView"
            android:gravity="center"
            android:text="Show Date"
            android:textColor="#000"
            android:textSize="10dp" />

        <TextView
            android:id="@+id/ShowLocationTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignStart="@+id/ShowDateTextView"
            android:layout_below="@+id/ShowDateTextView"
            android:gravity="center"
            android:text="Show Location"
            android:textColor="#000"
            android:textSize="10dp" />

        <TextView
            android:id="@+id/ShowTypeTextView"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_alignStart="@+id/ShowDateTextView"
            android:layout_below="@+id/ShowLocationTextView"
            android:gravity="center"
            android:text="Show Type"
            android:textColor="#000"
            android:textSize="10dp" />

      <!--  <android.support.v7.widget.AppCompatImageView
            android:id="@+id/ShowImageView"
            android:layout_width="90dp"
            android:layout_height="50dp"
            android:layout_alignStart="@+id/ShowTypeTextView"
            android:layout_below="@+id/ShowTypeTextView" />-->



    </RelativeLayout>
</android.support.v7.widget.CardView>

这是我的数据库结构

enter image description here 

    java.lang.NullPointerException: Attempt to invoke virtual method 'void 
    android.support.v7.widget.RecyclerView.setHasFixedSize(boolean)' on a 
    null object reference

这是我的日志猫

enter image description here

see this is my new database

In my App it looks like this

Logcat

最佳答案

即使我看不到您的数据库结构，我也可以从您的代码中看出您要求 Street Problems 下的所有内容，其中包括您之前推送的所有对象。我从错误消息中可以看到，它正在尝试为在 Street Problems 节点下找到的推送 ID -L57t4-97c3dLZjA_yXC 查找 setter 或字段。如果您想获取单个对象，则必须深入研究 Street Problems 下的推送 ID 中的对象。您的代码应如下所示:

dataSnapshot.child("Street Problems/-L57t4-97c3dLZjA_yXC").getValue(StreetClass.class);

如果您想要所有 StreetClass 对象，则只需像这样循环遍历其子对象即可:

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference yourRef = rootRef.child("Street Problems");
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            for(DataSnapshot dSnapshot : ds.getChildren()) {
                StreetClass streetClass = dSnapshot.getValue(StreetClass.class);
                Log.d("TAG", streetClass.getName());
            }
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
yourRef.addListenerForSingleValueEvent(eventListener);

这是有关如何使用 getName() 方法显示名称的示例。

编辑:

正如我在您更新的问题中看到的，警告是因为您的字段和 setter 之间的大小写不匹配。

您有一个名为的字段以及相应的 setter 和 getter，但它们不正确!

private String sname;

public String getName() {
    return sname;
}

public void setName(String name) {
    this.sname = name;
}

正确的 setter 和 getter 应该是:

public String getSname() {
    return sname;
}

public void setSname(String name) {
    this.sname = name;
}

其他领域也存在同样的问题。

这是构建模型类的正确方法:

public class StreetClass {
    private String id;
    private String semail;
    private String sname;
    private String stype;
    private String sdetail;
    private String slocation;
    private String sdate;
    private String imgurl;

    public StreetClass(){}

    public StreetClass(String id, String semail, String sname, String stype, String sdetail, String slocation, String sdate, String imgurl) {
        this.id = id;
        this.semail = semail;
        this.sname = sname;
        this.stype = stype;
        this.sdetail = sdetail;
        this.slocation = slocation;
        this.sdate = sdate;
        this.imgurl = imgurl;
    }

    public String getId() {
        return id;
    }

    public void setId(String id) {
        this.id = id;
    }

    public String getSemail() {
        return semail;
    }

    public void setSemail(String semail) {
        this.semail = semail;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public String getStype() {
        return stype;
    }

    public void setStype(String stype) {
        this.stype = stype;
    }

    public String getSdetail() {
        return sdetail;
    }

    public void setSdetail(String sdetail) {
        this.sdetail = sdetail;
    }

    public String getSlocation() {
        return slocation;
    }

    public void setSlocation(String slocation) {
        this.slocation = slocation;
    }

    public String getSdate() {
        return sdate;
    }

    public void setSdate(String sdate) {
        this.sdate = sdate;
    }

    public String getImgurl() {
        return imgurl;
    }

    public void setImgurl(String imgurl) {
        this.imgurl = imgurl;
    }
}

您还可以使用 String 类，如下所示:

DatabaseReference rootRef = FirebaseDatabase.getInstance().getReference();
DatabaseReference yourRef = rootRef.child("Street Problems");
ValueEventListener eventListener = new ValueEventListener() {
    @Override
    public void onDataChange(DataSnapshot dataSnapshot) {
        for(DataSnapshot ds : dataSnapshot.getChildren()) {
            for(DataSnapshot dSnapshot : ds.getChildren()) {
                String sname = dSnapshot.child("sname").getValue(String.class);
                Log.d("TAG", sname);
            }
        }
    }

    @Override
    public void onCancelled(DatabaseError databaseError) {}
};
yourRef.addListenerForSingleValueEvent(eventListener);

关于java - 带类映射器 : No setter/field for class，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/48742022/

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