在RecyclerView中看不到任何条目

Question

我已经在Android Studio中创建了RecyclerView，就像在另一个片段中一样。 问题在于，所有功能都可以在第一时间使用，但是在创建行对象并说明应用程序后，我看不到任何条目。 我做了这个RecyclerView的方法与我以前使用的效果很好的方法相同。我进行了很多搜索，但发现了错误。

这是我的片段xml：

 <android.support.v4.widget.SwipeRefreshLayout xmlns:android="http://schemas.android.com/apk/res/android" android:id="@+id/training_swiperefresh" android:layout_width="match_parent" android:layout_height="match_parent"> <RelativeLayout android:layout_width="match_parent" android:layout_height="match_parent"> <TextView android:id="@+id/trainingtTitle" android:layout_width="match_parent" android:layout_height="wrap_content" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:layout_marginTop="0dp" android:layout_marginBottom="16dp" android:textStyle="bold" android:textColor="@color/colorPrimary" android:text="@string/trainingTitle" /> <android.support.v7.widget.RecyclerView android:id="@+id/training_recycler_view" android:layout_width="match_parent" android:layout_height="wrap_content" android:scrollbars="vertical" android:layout_below="@+id/trainingtTitle" /> </RelativeLayout> </android.support.v4.widget.SwipeRefreshLayout> 

这是RecyclerView的行布局：

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_height="wrap_content" android:layout_width="match_parent" android:focusable="true" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:clickable="true" android:background="?android:attr/selectableItemBackground" android:orientation="vertical"> <!-- Plan icon --> <ImageView android:id="@+id/planImage" android:layout_width="24dp" android:layout_height="24dp" android:layout_centerVertical="true" android:layout_alignParentStart="true" android:layout_marginRight="8dp" android:layout_marginTop="1dp" android:layout_marginBottom="1dp" android:contentDescription="Icon" android:src="@drawable/ic_menu_train" /> <!-- Plan title --> <TextView android:id="@+id/planTitle" android:textColor="@color/colorBlack" android:layout_width="match_parent" android:layout_marginLeft="40dp" android:layout_marginRight="40dp" android:layout_marginTop="14dp" android:textSize="16dp" android:layout_height="wrap_content" /> <!-- Plan type --> <TextView android:id="@+id/planType" android:layout_below="@id/planTitle" android:layout_marginLeft="40dp" android:layout_marginRight="40dp" android:layout_width="match_parent" android:layout_height="wrap_content" /> <!-- Plan date --> <TextView android:id="@+id/planDate" android:layout_width="match_parent" android:layout_below="@id/planType" android:layout_marginLeft="42dp" android:layout_marginRight="40dp" android:layout_marginBottom="14dp" android:layout_height="wrap_content" /> <!-- Plan view --> <ImageView android:id="@+id/planView" android:layout_width="24dp" android:layout_height="24dp" android:layout_alignParentEnd="true" android:layout_centerVertical="true" android:layout_marginTop="1dp" android:layout_marginBottom="1dp" android:contentDescription="Icon" android:src="@drawable/ic_menu_show" /> <View android:layout_width="fill_parent" android:layout_height="1dip" android:layout_below="@id/planDate" android:layout_marginLeft="42dp" android:background="#DCDCDC" /> </RelativeLayout> 

这是我称为适配器的片段：

 public class TrainingFragment extends Fragment { private OnFragmentInteractionListener mListener; // Variables for Recycler View private List<Plans> planList = new ArrayList<>(); private RecyclerView trainingRecyclerView; private PlansAdapter pAdapter; public TrainingFragment() { // Required empty public constructor } //Change the title in action bar public void onResume() { super.onResume(); String titleString = getResources().getString(R.string.title_activity_navigation_drawer_training); // Set title bar ((NavigationDrawerActivity) getActivity()) .setActionBarTitle(titleString); } public static TrainingFragment newInstance() { TrainingFragment fragment = new TrainingFragment(); return fragment; } @Override public void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); // Menü bekannt geben, dadurch kann Fragment Menü-Events verarbeiten setHasOptionsMenu(true); } //Fragment XML geben, sowie als Menü setzen @Override public void onCreateOptionsMenu(Menu menu, MenuInflater inflater) { inflater.inflate(R.menu.menu_training, menu); // Declare ImageView and Animation for rotation animation MenuItem reloadButton = (MenuItem) menu.findItem(R.id.menu_reloadbutton); final Animation rotation = AnimationUtils.loadAnimation(getActivity(), R.anim.animation_rotate); //if (reloadButton != null) { // //reloadButton.setImageResource(R.drawable.ic_menu_reloadentry); // reloadButton.getActionView().setOnClickListener(new View.OnClickListener() { // @Override // public void onClick(View view) { // rotation.setRepeatCount(Animation.INFINITE); // view.startAnimation(rotation); // } // }); //} } //AddEntry click abfangen und verarbeiten @Override public boolean onOptionsItemSelected(MenuItem item) { // Wir prüfen, ob Menü-Element mit der ID "action_daten_aktualisieren" // ausgewählt wurde und geben eine Meldung aus int id = item.getItemId(); if (id == R.id.menu_reloadbutton) { // Text ausgeben //Toast.makeText(getActivity(), "Liste aktualisieren gedrückt!", Toast.LENGTH_LONG).show(); return true; } return super.onOptionsItemSelected(item); } @Override public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) { // Inflate the layout for this fragment View view = inflater.inflate(R.layout.fragment_training, container, false); // Get Refresh Layout SwipeRefreshLayout swipeRefreshLayout = (SwipeRefreshLayout) view.findViewById(R.id.training_swiperefresh); // Change color for the refresh layout swipeRefreshLayout.setColorSchemeColors(Color.rgb(99, 195, 195)); trainingRecyclerView = (RecyclerView) view.findViewById(R.id.training_recycler_view); pAdapter = new PlansAdapter(planList, getContext()); RecyclerView.LayoutManager pLayoutManager = new LinearLayoutManager(getActivity().getApplicationContext()); trainingRecyclerView.setLayoutManager(pLayoutManager); trainingRecyclerView.setItemAnimator(new DefaultItemAnimator()); trainingRecyclerView.setAdapter(pAdapter); preparePlansData(); return view; } private void preparePlansData() { // Set plan data Plans plan = new Plans("ABC-Bestellung", "Muskelaufbau", "Datum: 21.04.1997"); // Add Object to list planList.add(plan); plan = new Plans("test", "tttt", "ttttt"); planList.add(plan); // Notify data changes pAdapter.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); } @Override public void onStart() { super.onStart(); try { mListener = (OnFragmentInteractionListener) getActivity(); } catch (ClassCastException e) { throw new ClassCastException(getActivity().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); } } 

这是我的适配器：

 public class PlansAdapter extends RecyclerView.Adapter<PlansAdapter.MyPlanHolder> { private List<Plans> planList; private final Context customContext; public class MyPlanHolder extends RecyclerView.ViewHolder { public TextView planTitle, planType, planDate; public MyPlanHolder(View view) { super(view); planTitle = (TextView) view.findViewById(R.id.planTitle); planType = (TextView) view.findViewById(R.id.planType); planDate = (TextView) view.findViewById(R.id.planDate); } } public PlansAdapter(List<Plans> planList, Context customContext) { this.planList = planList; this.customContext = customContext; } @Override public MyPlanHolder onCreateViewHolder(ViewGroup parent, int viewType) { View itemView = LayoutInflater.from(parent.getContext()) .inflate(R.layout.plans_list_row, parent, false); return new MyPlanHolder(itemView); } @Override public void onBindViewHolder(MyPlanHolder holder, int position) { final Plans plan = planList.get(position); holder.planTitle.setText(plan.getPlanTitle()); holder.planType.setText(plan.getPlanType()); holder.planDate.setText(plan.getPlanDate()); } @Override public int getItemCount() { return 0; } } 

最后我的对象类的元素：

 public class Plans { private String planTitle, planType, planDate; public Plans(String planTitle, String planType, String planDate) { this.planTitle = planTitle; this.planType = planType; this.planDate = planDate; } public void setPlanTitle(String planTitle) { this.planTitle = planTitle; } public String getPlanTitle() { return planTitle; } public void setPlanType(String planType) { this.planType = planType; } public String getPlanType() { return planType; } public void setPlanDate(String planDate) { this.planDate = planDate; } public String getPlanDate() { return planDate; } } 

希望您能找到问题。

Answer 1

在Adapter的getItemCount（）方法中，您将返回0作为列表的大小，应将其更改为return planList.size（）

Answer 2

您的代码很好，除非在适配器中要在getItemCount（）方法中返回0。

这是更新的代码：

 public class PlansAdapter extends RecyclerView.Adapter<PlansAdapter.MyPlanHolder> {

private List<Plans> planList;
private final Context customContext;

public class MyPlanHolder extends RecyclerView.ViewHolder {

    public TextView planTitle, planType, planDate;

    public MyPlanHolder(View view) {
        super(view);
        planTitle = (TextView) view.findViewById(R.id.planTitle);
        planType = (TextView) view.findViewById(R.id.planType);
        planDate = (TextView) view.findViewById(R.id.planDate);
    }
}

public PlansAdapter(List<Plans> planList, Context customContext) {
    this.planList = planList;
    this.customContext = customContext;
}

@Override
public MyPlanHolder onCreateViewHolder(ViewGroup parent, int viewType) {
    View itemView = LayoutInflater.from(parent.getContext())
            .inflate(R.layout.plans_list_row, parent, false);

    return new MyPlanHolder(itemView);
}

@Override
public void onBindViewHolder(MyPlanHolder holder, int position) {

    final Plans plan = planList.get(position);

    holder.planTitle.setText(plan.getPlanTitle());
    holder.planType.setText(plan.getPlanType());
    holder.planDate.setText(plan.getPlanDate());

}

@Override
public int getItemCount() {
    return planList.size();
}
}