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我有一個使用片段的NavigationDrawer活動。在我的一個片段中，我想將Firebase數據庫中的數據加載到RecyclerView中。Android - 從片段中的Firebase數據庫加載數據
所以我有一個ArrayList的對象，我已經存儲在數據庫中。然後，我將一個ValueEventListener添加到數據庫引用中，將數據庫中的對象添加到數組列表中。然後，我將ArrayList傳遞給RecyclerView適配器，它將使用我的對象創建列表。
當我使用addListenerForSingleValueEvent它永遠不會工作，我總是得到一個空的RecyclerView。當我使用addValueEventListener時，它在開始時都不工作，但是當我將手機的方向切換爲橫向時，數據突然出現。如果我回到正常的方向，它仍然存在。但在開始的時候我並沒有打開片段。
這裏是我的片段類代碼：
public class LogFragment extends Fragment {
private RecyclerView recyclerView;
private RecyclerView.Adapter rvAdapter;
private RecyclerView.LayoutManager rvLayoutManager;
private ArrayList<LogEntry> entries;
private DatabaseReference databaseReference;
private DatabaseReference logReference;
private FirebaseAuth firebaseAuth;
private FirebaseUser firebaseUser;
public LogFragment() {
// Required empty public constructor
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {
View rootView = inflater.inflate(R.layout.fragment_log, container, false);
databaseReference = FirebaseDatabase.getInstance().getReference();
firebaseAuth = FirebaseAuth.getInstance();
firebaseUser = firebaseAuth.getCurrentUser();
loadEntries();
recyclerView = (RecyclerView) rootView.findViewById(R.id.recyclerView);
rvLayoutManager = new LinearLayoutManager(getActivity());
recyclerView.setLayoutManager(rvLayoutManager);
rvAdapter = new RvAdapter(entries);
recyclerView.setAdapter(rvAdapter);
// Inflate the layout for this fragment
return rootView;
}
private void loadEntries(){
entries = new ArrayList<>();
logReference = databaseReference.child("log").child(firebaseUser.getUid());
ValueEventListener valueEventListener = new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for(DataSnapshot ds : dataSnapshot.getChildren()){
entries.add(ds.getValue(LogEntry.class));
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
Log.w("LogFragment", "loadLog:onCancelled", databaseError.toException());
}
};
logbuchReference.addValueEventListener(valueEventListener);
}
}
這裏是我的RvAdapter.java：
public class RvAdapter extends RecyclerView.Adapter<RvAdapter.MyViewHolder> {
private ArrayList<LogEntry> entries;
public RvAdapter(ArrayList<LogEntry> entries){
this.entries = entries;
}
@Override
public MyViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
View itemView = LayoutInflater.from(parent.getContext()).inflate(R.layout.log_entry_item, null);
return new MyViewHolder(itemView);
}
@Override
public void onBindViewHolder(MyViewHolder holder, int position) {
SimpleDateFormat dateFormat = new SimpleDateFormat("dd.MM.yyyy");
SimpleDateFormat timeFormat = new SimpleDateFormat("HH:mm");
holder.tvAction.setText(entries.get(position).action);
holder.tvDate.setText(dateFormat.format(entries.get(position).date)+"\n"+timeFormat.format(entries.get(position).date));
holder.ivIcon.setImageResource(entries.get(position).icon);
holder.itemView.setOnClickListener(new View.OnClickListener(){
@Override
public void onClick(View v) {
// Do something
}
});
}
@Override
public int getItemCount() {
return entries.size();
}
public class MyViewHolder extends RecyclerView.ViewHolder {
TextView tvAction, tvDate;
ImageView ivIcon;
public MyViewHolder(View itemView) {
super(itemView);
tvAction = (TextView) itemView.findViewById(R.id.tvAction);
tvDate = (TextView) itemView.findViewById(R.id.tvDate);
ivIcon = (ImageView) itemView.findViewById(R.id.ivIcon);
}
}
}
在這裏，我LogEntry.java：
public class LogEntry {
public String action;
public Date date;
public int icon;
public String message;
public LogEntry() {}
public LogEntry(String action, Date date, int icon, String message) {
this.action = action;
this.date = date;
this.icon = icon;
this.message = message;
}
}
有人知道可能是什麼問題？
編輯：
當我之後System.out.prinln的ArrayList中的（）我得到的數據。所以從數據庫加載數據正在工作。但呈現數據不起作用。