Android Firebase数据到RecyclerView仅显示一项

我正在从firebase检索数据，并试图在recycler视图中显示，一切正常，但列表中只显示一项（总共有14项）

如果您不理解问题，请发表评论

这是我从firebase获取数据快照的主要活动

public class cakes_activity extends AppCompatActivity {
RecyclerView recyclerView;
ArrayList<Data> listdata;
private DatabaseReference mref;
private  NorthAdaptor north;
private final Context context = this;


public int counter = 0;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_cakes);
    Toolbar toolbar = (Toolbar) findViewById(R.id.toolbar);
    EditText editText = (EditText) findViewById(R.id.editText) ;
    setSupportActionBar(toolbar);
    getSupportActionBar().setDisplayHomeAsUpEnabled(true);
    //FIREBASE
    recyclerView = (RecyclerView) findViewById(R.id.recycler_view);
    mref= FirebaseDatabase.getInstance().getReference("Cakes");
    mref.addChildEventListener(new ChildEventListener() {
        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
            Data data = dataSnapshot.getValue(Data.class);
            listdata = new ArrayList<>();
            listdata.add(data);
            north = new NorthAdaptor(context,listdata);
            recyclerView.setLayoutManager(new LinearLayoutManager(context));
            recyclerView.hasFixedSize();
            recyclerView.setAdapter(north);

        }

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



        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {



        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {



        }

        @Override
        public void onCancelled(DatabaseError databaseError) {



        }
    });

}

public class Data {
private String ID,Name,image,RS;
public Data(){

}

public Data(String ID, String Name, String image, String RS) {
    this.ID = ID;
    this.Name = Name;
    this.image= image;
    this.RS = RS;
}

public String getId() {
    return ID;
}
public String getRS() {
    return RS;
}

public void setId(String id) {

    this.ID = id;
}

public String getName() {
    return Name;
}

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

public String getimage() {
    return image;
}

public void setImg(String image) {
    this.image = image;
}

}

listdata=newarraylist（）；
north=新的NorthAdapter（上下文，listdata）；
setLayoutManager（新的LinearLayoutManager（上下文））；
RecycleView.hasFixedSize（）；
recyclerView.setAdapter（北部）；

您需要用onCreate而不是onchildaded编写此代码

public class Data {
private String ID,Name,image,RS;
public Data(){

}

public Data(String ID, String Name, String image, String RS) {
    this.ID = ID;
    this.Name = Name;
    this.image= image;
    this.RS = RS;
}

public String getId() {
    return ID;
}
public String getRS() {
    return RS;
}

public void setId(String id) {

    this.ID = id;
}

public String getName() {
    return Name;
}

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

public String getimage() {
    return image;
}

public void setImg(String image) {
    this.image = image;
}

listdata = new ArrayList<>();

        north = new NorthAdaptor(context,listdata);
        recyclerView.setLayoutManager(new LinearLayoutManager(context));
        recyclerView.hasFixedSize();
        recyclerView.setAdapter(north);