我已经调查了几个关于这个问题的答案（这里，这里，这里），但是没有一个建议的解决方案是有效的。我的问题是没有显示我的recyclerview列表项。我在messengerrecycleradapter、oncreateviewholder、onbindviewholder和getitemcount中设置了断点，只调用了第一个断点。在断点中，我输入了表达式计算器并执行

MessengerRecyclerAdapter.getItemCount();

得到了预期的20分。recyclerview本身占据了预期的内容区域，如下面的屏幕截图所示（我将recyclerview变成了洋红色以突出显示它所占据的空间）。

我的recyclerview xml代码如下：

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="match_parent"
          android:layout_height="match_parent"
          android:orientation="vertical">

<android.support.v7.widget.RecyclerView
    android:id="@+id/thread_list"
    android:background="@color/colorAccent"
    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:name="com.jypsee.jypseeconnect.orgPicker.MessengerListFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:layoutManager="LinearLayoutManager"
    tools:context="com.jypsee.jypseeconnect.orgPicker.MessengerListFragment"
    tools:listitem="@layout/fragment_messenger_cell"/>

</LinearLayout>

我的recyclerview单元格xml:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
          android:layout_width="wrap_content"
          android:layout_height="wrap_content"
          android:orientation="horizontal">

<TextView
    android:id="@+id/id"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="@dimen/text_margin"
    android:textAppearance="?attr/textAppearanceListItem"
    android:textColor="@color/blueText"/>

<TextView
    android:id="@+id/content"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_margin="@dimen/text_margin"
    android:textAppearance="?attr/textAppearanceListItem"
    android:textColor="@color/darkText"/>
</LinearLayout>

我的listfragment类：

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

    List<DummyContent.DummyItem> items = new ArrayList<>();
    for (Integer i = 0; i<20; i++){
        DummyContent.DummyItem item = new DummyContent.DummyItem(i.toString(),"Content","Details");
        items.add(item);
    }

    View view = inflater.inflate(R.layout.fragment_messenger_list, container, false);
    mRecyclerView = (RecyclerView) view.findViewById(R.id.thread_list);
    mRecyclerView.setLayoutManager(new LinearLayoutManager(getActivity()));
    mRecyclerAdapter = new MessengerThreadRecyclerAdapter(items, mListener);
    mRecyclerView.setAdapter(mRecyclerAdapter);
    mRecyclerAdapter.notifyDataSetChanged();
    return view;
}

我的适配器类：

public class MessengerRecyclerAdapter
    extends RecyclerView.Adapter<MessengerRecyclerAdapter.MessageThreadHolder>{

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

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

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

@Override
public void onBindViewHolder(final MessageThreadHolder holder, final 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 (mListener != null) {
                mListener.recyclerViewListClicked(v, position);
            }
        }
    });
}

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

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

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

}
如您所见，我已将linearlayout方向设置为“垂直”，并设置了布局管理器，这是两种最常见的解决方案。我真的不知道下一步该做什么，所以任何帮助我都很感激。