我正在创建一个fragment，用于从服务器加载notifications数据并显示在recyclerview中。数据已从服务器正确加载。但recycler view中未显示fragment。
logcat中未显示任何错误。
片段（此片段默认加载导航抽屉（主片段）。）：
/**
* A simple {@link Fragment} subclass.
* Activities that contain this fragment must implement the
* {@link HomeFragment.OnFragmentInteractionListener} interface
* to handle interaction events.
* Use the {@link HomeFragment#newInstance} factory method to
* create an instance of this fragment.
*/
public class HomeFragment extends Fragment {
// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private static final String ARG_PARAM1 = "param1";
private static final String ARG_PARAM2 = "param2";
private SessionManagement session;
private Context mContext;
private RequestQueue requestQueue;
private Gson gson;
private RecyclerView recyclerViewNotifications;
private List<Notifications> listNotifications;
private NotificationsRecyclerAdapter notificationsRecyclerAdapter;
private String loggedUserId;
// TODO: Rename and change types of parameters
private String mParam1;
private String mParam2;
private OnFragmentInteractionListener mListener;
public HomeFragment() {
// Required empty public constructor
}
/**
* Use this factory method to create a new instance of
* this fragment using the provided parameters.
*
* @param param1 Parameter 1.
* @param param2 Parameter 2.
* @return A new instance of fragment HomeFragment.
*/
// TODO: Rename and change types and number of parameters
public static HomeFragment newInstance(String param1, String param2) {
HomeFragment fragment = new HomeFragment();
Bundle args = new Bundle();
args.putString(ARG_PARAM1, param1);
args.putString(ARG_PARAM2, param2);
fragment.setArguments(args);
return fragment;
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
if (getArguments() != null) {
mParam1 = getArguments().getString(ARG_PARAM1);
mParam2 = getArguments().getString(ARG_PARAM2);
}
}
@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
Bundle savedInstanceState) {
// Inflate the layout for this fragment
return inflater.inflate(R.layout.fragment_home, container, false);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//----------------------------------------------------------------------------------------
// Session class instance
session = new SessionManagement(getActivity().getApplicationContext());
// get user data from session
HashMap<String, String> user = session.getUserDetails();
String loggedUserId = user.get(SessionManagement.KEY_USERID);
//----------------------------------------------------------------------------------------
mContext = getActivity().getBaseContext();
recyclerViewNotifications = (RecyclerView) view.findViewById(R.id.recyclerViewNotifications);
listNotifications = new ArrayList<>();
notificationsRecyclerAdapter = new NotificationsRecyclerAdapter(listNotifications);
RecyclerView.LayoutManager mLayoutManager = new LinearLayoutManager(getActivity().getApplicationContext());
recyclerViewNotifications.setLayoutManager(mLayoutManager);
recyclerViewNotifications.addItemDecoration(new DividerItemDecoration(mContext, LinearLayoutManager.VERTICAL));
recyclerViewNotifications.setItemAnimator(new DefaultItemAnimator());
recyclerViewNotifications.setHasFixedSize(true);
// Manually checking internet connection
//if network not available
if (!ConnectivityReceiver.isConnected()) {
Log.d("x", "inside offline work.........View List");
//Toast.makeText(mContext, "view list", Toast.LENGTH_SHORT).show();
// launch new intent instead of loading fragment
} else {
//if network available
Log.d("c", "inside online work.........Fetch notifications data");
//Toast.makeText(getBaseContext(), "fetch enquiries", Toast.LENGTH_SHORT).show();
requestQueue = null;
// Get a RequestQueue
requestQueue = Volley.newRequestQueue(mContext);
fetchNotifications(loggedUserId);
}
//setting itemclick listener
ItemClickSupport.addTo(recyclerViewNotifications).setOnItemClickListener(new ItemClickSupport.OnItemClickListener() {
@Override
public void onItemClicked(RecyclerView recyclerView, int position, View v) {
// do it
/* Notifications noti=(Notifications) recyclerViewNotifications.getMyNotification(position);
Intent viewIntent=new Intent(mContext, EnquiryViewActivity.class);
if(enquiry!=null) {
Log.d("dash", "get enqid" + enquiry.getId());
viewIntent.putExtra("EnquiryId",enquiry.getId());
viewIntent.putExtra("UserId",enquiry.getUser_id());
}
startActivity(viewIntent);*/
}
});
try {
recyclerViewNotifications.setAdapter(notificationsRecyclerAdapter);
}catch (NullPointerException e){
Log.d("Error :","No notifications exists!");
//Toast.makeText(mContext,"No business details exists!",Toast.LENGTH_LONG).show();
}
listNotifications.clear();
try {
fetchNotifications(loggedUserId);
// listNotifications.addAll();
}catch (NullPointerException e){
Log.d("sdfs", "No Data available");
}
notificationsRecyclerAdapter.notifyDataSetChanged();
}
// TODO: Rename method, update argument and hook method into UI event
public void onButtonPressed(Uri uri) {
if (mListener != null) {
mListener.onFragmentInteraction(uri);
}
}
@Override
public void onAttach(Context context) {
super.onAttach(context);
// if (context instanceof OnFragmentInteractionListener) {
// mListener = (OnFragmentInteractionListener) context;
// } else {
// throw new RuntimeException(context.toString()
// + " must implement OnFragmentInteractionListener");
// }
}
@Override
public void onDetach() {
super.onDetach();
mListener = null;
}
/**
* This interface must be implemented by activities that contain this
* fragment to allow an interaction in this fragment to be communicated
* to the activity and potentially other fragments contained in that
* activity.
* <p>
* See the Android Training lesson <a href=
* "http://developer.android.com/training/basics/fragments/communicating.html"
* >Communicating with Other Fragments</a> for more information.
*/
public interface OnFragmentInteractionListener {
// TODO: Update argument type and name
void onFragmentInteraction(Uri uri);
}
//-----------------------------------------------------------------------------------------
private void fetchNotifications(final String LogId) {
/*// Get a RequestQueue
// RequestQueue requestQueue = MyVolleySingleton.getInstance(this.getApplicationContext()).getRequestQueue();
requestQueue = Volley.newRequestQueue(this);*/
//create gson instance which is used to parse json
GsonBuilder gsonBuilder = new GsonBuilder();
gsonBuilder.excludeFieldsWithoutExposeAnnotation();
//gsonBuilder.setDateFormat("M/d/yy hh:mm a");
gson = gsonBuilder.create();
StringRequest sr = new StringRequest(Request.Method.POST, EndPoints.GET_ALL_NOTIFICATIOS_URL, new Response.Listener<String>() {
@Override
public void onResponse(String response) {
Log.d("d", "getting response.........\n" + response);
//Toast.makeText(getApplicationContext(), "Enquiry JSON data :" + response, Toast.LENGTH_LONG).show();
List<Notifications> notiList = Arrays.asList(gson.fromJson(response, Notifications[].class));
/* for (Notifications noti : notiList) {
listNotifications.add(noti);
}*/
listNotifications.addAll(notiList);
}
}, new Response.ErrorListener() {
@Override
public void onErrorResponse(VolleyError error) {
Log.e("MainActivity", error.toString());
Toast.makeText(mContext, "Error: " + error.getMessage(), Toast.LENGTH_LONG).show();
}
}) {
@Override
protected Map<String, String> getParams() throws AuthFailureError {
Log.d("d", "inside getparams()...\n");
Map<String, String> params = new HashMap<String, String>();
params.put("userid", LogId);
Log.d("d", "userid to pass:" + LogId + "\n");
return params;
}
};
// Add the request to RequestQueue.
// MyVolleySingleton.getInstance(this).addToRequestQueue(sr);
requestQueue.add(sr);
Log.d("d", "Added to queue");
}
}
适配器：
public class NotificationsRecyclerAdapter extends RecyclerView.Adapter<NotificationsRecyclerAdapter.NotificationsViewHolder> {
private List<Notifications> listNotifications;
public NotificationsRecyclerAdapter(List<Notifications> listNotifications) {
this.listNotifications = listNotifications;
}
public Notifications getMyNotification(int position) {
Log.d("EnquiryAdapter : ", "position: " + position);
Log.d("EnquiryAdapter : ", "item : " + listNotifications.get(position).getId());
return listNotifications.get(position);
}
@Override
public NotificationsRecyclerAdapter.NotificationsViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
// inflating recycler item view
View itemView = LayoutInflater.from(parent.getContext())
.inflate(R.layout.item_notifications_recycler, parent, false);
return new NotificationsViewHolder(itemView);
}
@Override
public void onBindViewHolder(NotificationsViewHolder holder, int position) {
Notifications noti=new Notifications();
Log.d("NotificationsAdapter : ", "type : " + noti.getAction());
Log.d("NotificationsAdapter : ", "status : " + noti.getCreateddate());
holder.textViewNotiAction.setText(listNotifications.get(position).getAction());
holder.textViewNotiDate.setText(listNotifications.get(position).getCreateddate());
}
@Override
public int getItemCount() {
Log.v(NotificationsRecyclerAdapter.class.getSimpleName(), "" + listNotifications.size());
return listNotifications.size();
}
/**
* ViewHolder class
*/
public class NotificationsViewHolder extends RecyclerView.ViewHolder {
public AppCompatTextView textViewNotiAction;
public AppCompatTextView textViewNotiDate;
public NotificationsViewHolder(View view) {
super(view);
textViewNotiAction = (AppCompatTextView) view.findViewById(R.id.textViewNotiAction);
textViewNotiDate = (AppCompatTextView) view.findViewById(R.id.textViewNotiDate);
}
}
}
片段布局：
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
tools:context="com.example.anjana.decorightkitchen.fragment.HomeFragment">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">
<ScrollView
android:layout_width="match_parent"
android:layout_height="match_parent">
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerViewNotifications"
android:layout_width="match_parent"
android:layout_height="match_parent" />
</ScrollView>
</LinearLayout>
</FrameLayout>
项目布局：
<?xml version="1.0" encoding="utf-8"?>
<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:layout_width="match_parent"
android:layout_height="wrap_content"
card_view:cardCornerRadius="4dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical"
android:padding="16dp">
<LinearLayout
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="horizontal">
<android.support.v7.widget.AppCompatTextView
android:id="@+id/textViewNotiAction"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_weight="1"
android:text="Notification"
android:textStyle="bold"
android:textColor="@color/colorAccentBlue" />
<android.support.v7.widget.AppCompatTextView
android:id="@+id/textViewNotiDate"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="end"
android:layout_weight="1"
android:text="date"
android:textColor="@color/colorHintText" />
</LinearLayout>
</LinearLayout>
</android.support.v7.widget.CardView>
答案 0 :(得分：0)
从服务获取列表后，必须将更新的listNotifications发送到适配器，然后设置适配器。
@Override
public void onResponse(String response) {
Log.d("d", "getting response.........\n" + response);
List<Notifications> notiList = Arrays.asList(gson.fromJson(response, Notifications[].class));
listNotifications.addAll(notiList);
notificationsRecyclerAdapter = new NotificationsRecyclerAdapter(listNotifications);
recyclerViewNotifications.setAdapter(notificationsRecyclerAdapter);
}
<强>更新
不要将RecylerView放入ScrollView（因为RecylerView有滚动），直到你想在同一页面中有两个滚动视图（例如2个recylerview），然后使用** NestedScrollView **进行嵌套滚动。
从底部提供一些余量
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerViewNotifications"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:layout_marginBottom="20dp" />
希望这会对你有所帮助。
答案 1 :(得分：0)
您使用空列表设置适配器，因此它不会显示 您必须定义适配器并在获得响应后使用值设置它：
@Override
public void onResponse(String response) {
Log.d("d", "getting response.........\n" + response);
//Toast.makeText(getApplicationContext(), "Enquiry JSON data :" + response, Toast.LENGTH_LONG).show();
List<Notifications> notiList = Arrays.asList(gson.fromJson(response, Notifications[].class));
/* for (Notifications noti : notiList) {
listNotifications.add(noti);
}*/
listNotifications.addAll(notiList);
notificationsRecyclerAdapter = new
NotificationsRecyclerAdapter(listNotifications);
recyclerViewNotifications.setAdapter(notificationsRecyclerAdapter);
}
或
@Override
public void onResponse(String response) {
Log.d("d", "getting response.........\n" + response);
//Toast.makeText(getApplicationContext(), "Enquiry JSON data :" + response, Toast.LENGTH_LONG).show();
List<Notifications> notiList = Arrays.asList(gson.fromJson(response, Notifications[].class));
/* for (Notifications noti : notiList) {
listNotifications.add(noti);
}*/
listNotifications.addAll(notiList);
notificationsRecyclerAdapter.notifyItemRangeInserted(0,listNotifications.size());
}
两种方式都相同但不确定它是否应该在代码中具有固定大小
recyclerViewNotifications.setHasFixedSize(true);
我想它应该在您的新列表设置后添加，希望它可以帮助您