Question

我想将我的Recycler视图包装在协调器布局中，但问题是每当我这样做时，项目就会停止显示。对于项目，我使用android studio中的自动生成的虚拟文本。如果我只使用没有coordinatorlayout的recylcer视图，所有项目都会完美显示。

提前感谢您的帮助。

p.s我在stackoverflow上提问时有点新意，所以我为任何格式问题道歉

fragment.java

public class TodoFragment extends Fragment {

    private static final String ARG_COLUMN_COUNT = "column-count";
    private OnListFragmentInteractionListener mListener;

    public TodoFragment() {
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
    }

    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container, Bundle savedInstanceState) {

        View view = inflater.inflate(R.layout.fragment_todo_list, container, false);
        final FloatingActionButton floatingActionButton = view.findViewById(R.id.fab);

        floatingActionButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

            }
        });

        if (view instanceof RecyclerView) {
            Context context = view.getContext();
            RecyclerView recyclerView = (RecyclerView) view;
            recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
            recyclerView.addItemDecoration(new DividerItemDecoration(getContext(), LinearLayoutManager.VERTICAL));
            recyclerView.setAdapter(new ToDoRecyclerViewAdapter(DummyContent.ITEMS, mListener));

        }
        return view;
    }


    @Override
    public void onAttach(Context context) {
        super.onAttach(context);
        if (context instanceof OnListFragmentInteractionListener) {
            mListener = (OnListFragmentInteractionListener) context;
        } else {
            throw new RuntimeException(context.toString()
                    + " must implement OnListFragmentInteractionListener");
        }
    }

    @Override
    public void onDetach() {
        super.onDetach();
        mListener = null;
    }

    public interface OnListFragmentInteractionListener {
        void onListFragmentInteraction(DummyItem item);
    }
}

layout.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.design.widget.CoordinatorLayout 
     xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/coordlayout"
     android:layout_width="match_parent"
     android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/list"
        android:name="com.example.kayc.projectplanner.aktivnostiFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"      
        app:layoutManager="com.example.kayc.projectplanner.FloatButtonBehavior.RVlayoutmanager"
        tools:context=".fragmenti.TodoFragment"
        tools:listitem="@layout/fragment_todo" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end|bottom"
        android:layout_margin="@dimen/fab_margin"    
        app:srcCompat="@android:drawable/ic_menu_add" />

</android.support.design.widget.CoordinatorLayout>

Adapter.java

public class ToDoRecyclerViewAdapter extends RecyclerView.Adapter<ToDoRecyclerViewAdapter.ViewHolder> {

    private final List<DummyItem> mValues;
    private final OnListFragmentInteractionListener mListener;

    public ToDoRecyclerViewAdapter(List<DummyItem> items, OnListFragmentInteractionListener listener) {
        mValues = items;
        mListener = listener;
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.fragment_todo, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final ViewHolder holder, int position) {
        holder.mItem = mValues.get(position);
        holder.mIdView.setText(mValues.get(position).id);
        holder.mContentView.setText(mValues.get(position).content);

        holder.mView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (null != mListener) {
                    mListener.onListFragmentInteraction(holder.mItem);
                }
            }
        });
    }

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

    public class ViewHolder extends RecyclerView.ViewHolder {
        public final View mView;
        public final TextView mIdView;
        public final TextView mContentView;
        public DummyItem mItem;

        public ViewHolder(View view) {
            super(view);
            mView = view;
            mIdView = (TextView) view.findViewById(R.id.item_number);
            mContentView = (TextView) view.findViewById(R.id.content);
        }

        @Override
        public String toString() {
            return super.toString() + " '" + mContentView.getText() + "'";
        }
    }
}

Answer 1

问题出在onCreateView。它应该是这样的：

@Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View view = inflater.inflate(R.layout.fragment_todo_list, container, false);

        final FloatingActionButton floatingActionButton = view.findViewById(R.id.fab);
        floatingActionButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

            }
        });

            RecyclerView recyclerView = (RecyclerView) view.findViewById(R.id.list);
            recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
            recyclerView.addItemDecoration(new DividerItemDecoration(getContext(), LinearLayoutManager.VERTICAL));
            recyclerView.setAdapter(new ToDoRecyclerViewAdapter(DummyContent.ITEMS, mListener));


        return view;
    }

if（查看instanceof RecyclerView）将始终返回false，因为view是ConstraintLayout实例。

Answer 2

if (view instanceof RecyclerView)永远不会执行。因为视图的根源是 CoordinatorLayout不是RecyclerView。所以只需删除if(view instanceof RecyclerView)。

<android.support.design.widget.CoordinatorLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/coordlayout"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/list"
        android:name="com.example.kayc.projectplanner.aktivnostiFragment"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_marginLeft="16dp"
        android:layout_marginRight="16dp"
        tools:context=".fragmenti.TodoFragment"
        tools:listitem="@layout/fragment_todo" />

    <android.support.design.widget.FloatingActionButton
        android:id="@+id/fab"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="end|bottom"
        android:layout_margin="@dimen/fab_margin"
        app:srcCompat="@android:drawable/ic_menu_add" />

</android.support.design.widget.CoordinatorLayout>

onCreateView()。

@Override
public View onCreateView(LayoutInflater inflater, ViewGroup container,
                         Bundle savedInstanceState) {
    View view = inflater.inflate(R.layout.fragment_todo_list, container, false);
    final FloatingActionButton floatingActionButton = view.findViewById(R.id.fab);
    floatingActionButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {

        }
    });
    RecyclerView recyclerView = view.findViewById(R.id.list);
    recyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    recyclerView.addItemDecoration(new DividerItemDecoration(getActivity(), LinearLayoutManager.VERTICAL));
    recyclerView.setAdapter(new ToDoRecyclerViewAdapter(DummyContent.ITEMS, mListener));

    return view;
}

同时查找onActivityCreated()因为getActivity()可以在onCreateView()中返回null。

未在回收站视图中显示的项目

2 个答案: