无法使用片段使 CustomAdapter 在循环中工作

Question

我正在尝试填充，使数据显示在我的列表视图中，但是当我单击该片段时，列表上没有任何内容。我试过将 setAdapter 移到循环内，但没有用。

我运行不知道如何让它发挥作用

以前有人试过用片段填充自定义适配器吗？？？

这是我的自定义适配器

import android.content.Context;
import android.support.annotation.LayoutRes;
import android.support.annotation.NonNull;
import android.support.annotation.Nullable;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.ArrayAdapter;
import android.widget.TextView;

import java.util.List;

/**
 * Created by calvi on 22/05/2018.
 */

public class MyListAdapter extends ArrayAdapter<User> {

    List<User> userList;
    Context context;
    int resource;

    public MyListAdapter(@NonNull Context context, @LayoutRes int resource, List<User> userList) {
        super(context, resource, userList);
        this.context = context;
        this.resource = resource;
        this.userList = userList;
    }

    @NonNull
    @Override
    public View getView(final int position, @Nullable View convertView, @NonNull ViewGroup parent) {

        //And for this we need a layoutinflater
        LayoutInflater layoutInflater = LayoutInflater.from(context);
        Log.d("listando", "Antes do inflater");
        //getting the view
        View view = layoutInflater.inflate(resource, null, false);
        Log.d("listando", "Depois do inflater");
        //getting the view elements of the list from the view
        TextView textViewName = view.findViewById(R.id.list_row);
        Log.d("listando", "Depois de pegar o textview");
        //getting the hero of the specified position
        User user = userList.get(position);
        Log.d("listando", "Depois de pegar o get pisition");
        //adding values to the list item
        textViewName.setText(user.getName());
        Log.d("listando", "Depois de setar o name");
        //finally returning the view
        return view;
    }
}

这是我的片段，它从 firebase 获取数据并将其填充到适配器上

import android.app.ProgressDialog;
import android.content.Intent;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.AdapterView;
import android.widget.ArrayAdapter;
import android.widget.ListView;
import android.widget.SimpleAdapter;
import android.widget.TextView;

import com.android.volley.Request;
import com.android.volley.RequestQueue;
import com.android.volley.Response;
import com.android.volley.VolleyError;
import com.android.volley.toolbox.StringRequest;
import com.android.volley.toolbox.Volley;
import com.google.firebase.database.ChildEventListener;
import com.google.firebase.database.DataSnapshot;
import com.google.firebase.database.DatabaseError;
import com.google.firebase.database.DatabaseReference;
import com.google.firebase.database.FirebaseDatabase;
import com.google.firebase.database.GenericTypeIndicator;

import org.json.JSONException;
import org.json.JSONObject;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;

public class UserMessageListFragment extends Fragment {

    private ProgressDialog progressDialog;
    private final String TAG = "UsersMessageLis";
    private ArrayList<String> arrayList = new ArrayList<>();
    ArrayList<HashMap<String, String>> mylist = new ArrayList<HashMap<String, String>>();
    private int totalUsers = 0;
    private ListView listView;
    private TextView noUsersText;
    private List<User> userList = new ArrayList<>();
    public static UserMessageListFragment newInstance() {
        return new UserMessageListFragment();
    }

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

        listView = view.findViewById(R.id.usersListListView);
        noUsersText = view.findViewById(R.id.noUsersText);

        final DatabaseReference refMessages = FirebaseDatabase.getInstance().getReference();
        final DatabaseReference ref= FirebaseDatabase.getInstance().getReference().child("usuarios");

        refMessages.addChildEventListener(new ChildEventListener() {
            @Override
            public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                if(dataSnapshot.getKey().contains(UserDetails.username+ "_")) {
                    final String[] userChatWithId = dataSnapshot.getKey().split(UserDetails.username+"_");

                    ref.addChildEventListener(new ChildEventListener() {
                        @Override
                        public void onChildAdded(DataSnapshot dataSnapshot, String s) {
                            if(dataSnapshot.getKey().equals(userChatWithId[1])) {
                                GenericTypeIndicator<Map<String, String>> genericTypeIndicator = new GenericTypeIndicator<Map<String, String>>() {};
                                Map<String, String> map = dataSnapshot.getValue(genericTypeIndicator);
                                String name = map.get("name").toString();
                                String username = map.get("username").toString();
                                String status = map.get("status").toString();
                                String city = map.get("city").toString();

                                Log.d("listando", name);
                                Log.d("listando", username);
                                Log.d("listando", status);
                                Log.d("listando", city);
                                User newUser = new User(username, status, city, name);

                                Log.d("Listando", newUser.toString());
                                userList.add(newUser);
////                                usersList.setAdapter(new ArrayAdapter<>(getContext(), R.layout.my_list, arrayList));
                            }
                        }

                        @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) {

                        }
                    });

                }
            }

            @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) {

            }
        });

        MyListAdapter adapter = new MyListAdapter(getContext(), R.layout.my_list, userList);

        //attaching adapter to the listview
        listView.setAdapter(adapter);

//        listView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
//            @Override
//            public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
//                UserDetails.chatWithId = arrayList.get(position);
//                startActivity(new Intent(getContext(), Chat.class));
//            }
//        });

        return view;
    }
//    public void doOnSuccess(String response) {
//
//        try {
//            JSONObject object = new JSONObject(response);
//            Iterator iterator = object.keys();
//            String key = "";
//
//            while(iterator.hasNext()) {
//                key = iterator.next().toString();
//
//                if(! key.equals(UserDetails.username)) {
//                    arrayList.add(key);
//                }
//                totalUsers++;
//            }
//
//        } catch (JSONException e) {
//            e.printStackTrace();
//        }
//
//        checkIfThereIsAnUser(totalUsers);
//    }
//    public void checkIfThereIsAnUser(int totalUsers) {
//
//
//        if(totalUsers <=1){
//            noUsersText.setVisibility(View.VISIBLE);
//            usersList.setVisibility(View.GONE);
//        }
//        else{
//            noUsersText.setVisibility(View.GONE);
//            usersList.setVisibility(View.VISIBLE);
//            usersList.setAdapter(new ArrayAdapter<>(getContext(), R.layout.my_list, arrayList));
//        }
//        progressDialog.dismiss();
//    }
}

我注意到适配器内的日志没有显示

Answer 1

创建适配器时

 MyListAdapter adapter = new MyListAdapter(getContext(), R.layout.my_list, userList);

userList 是空的。因此，当您向 userList 添加项目时，您必须 adapter.notifyDataSetChange() 更新您的适配器

Answer 2

尝试refMessages.addChildEventListener(getActivity(),new ChildEventListener() {......} 如果他们是碎片，请在每个听众中执行此操作。如果是 Activity 你不需要这样做。

无法使用片段使 CustomAdapter 在循环中工作

Unable to make CustomAdapter work in a Loop using Fragments

android

firebase

firebase-realtime-database

custom-adapter