我正在尝试将数据显示在我的Listview中，但是当我点击片段时，列表中没有任何内容。 我已经尝试在循环中移动setAdapter，但它不起作用。
我已经没有关于如何使其发挥作用的想法
是否有人试图在???
之前用片段填充自定义适配器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获取数据并在适配器上填充它
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
答案 0 :(得分：2)
创建适配器
时 MyListAdapter adapter = new MyListAdapter(getContext(), R.layout.my_list, userList);
userList为空。因此，当您向userList添加项目时，您必须adapter.notifyDataSetChange()更新您的适配器
答案 1 :(得分：0)
试试refMessages.addChildEventListener(getActivity(),new ChildEventListener() {......}
如果它们处于碎片中，则在每个听众中执行此操作。
如果是活动，您不需要这样做。