Android Studio 上面的预览是正确显示的，但是在手机上跑的时候RecyclerView就无法显示了。
本人大学狗一名，求大神指教

下面贴码

Adapter ：

package com.example.amoxicilin.null_test.adapter;

import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.TextView;

import com.example.amoxicilin.null_test.CommunicationFragment;
import com.example.amoxicilin.null_test.R;
import com.example.amoxicilin.null_test.adapter.DummyContent.DummyItem;

import java.util.List;

public class MyItemRecyclerViewAdapter extends RecyclerView.Adapter<MyItemRecyclerViewAdapter.ViewHolder> implements CommunicationFragment.OnListFragmentInteractionListener {

    private final List<DummyContent.DummyItem> mValues;
    private final CommunicationFragment.OnListFragmentInteractionListener mListener;
    public MyItemRecyclerViewAdapter(List<DummyContent.DummyItem> items, CommunicationFragment.OnListFragmentInteractionListener listener) {
        mValues = items;
        mListener = listener;
    }

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

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

        holder.mView.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if (null != mListener) {
                    // Notify the active callbacks interface (the activity, if the
                    // fragment is attached to one) that an item has been selected.
                    mListener.onListFragmentInteraction(holder.mItem);
                }
            }
        });
    }

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

    public void onListFragmentInteraction(DummyItem item) {

    }

    public class ViewHolder extends RecyclerView.ViewHolder {
        public final View mView;
        public final ImageView mImgTestView;
        public final TextView mTitleTestView;
        public final TextView mInfoTestView;
        public final Button mButtonLeft;
        public final Button mButtonRight;
        public DummyItem mItem;

        public ViewHolder(View view) {
            super(view);
            mView = view;
            mImgTestView= (ImageView) view.findViewById(R.id.ImgTest);
            mTitleTestView = (TextView) view.findViewById(R.id.TitleTest);
            mInfoTestView = (TextView) view.findViewById(R.id.InfoTest);
            mButtonLeft=(Button)view.findViewById(R.id.list_item_button_left);
            mButtonRight=(Button)view.findViewById(R.id.list_item_button_right);

        }

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

Activity
 ：
package com.example.amoxicilin.null_test;

import android.app.Fragment;
import android.content.Context;
import android.os.Bundle;
import android.support.v7.widget.GridLayoutManager;
import android.support.v7.widget.LinearLayoutManager;
import android.support.v7.widget.RecyclerView;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;

import com.example.amoxicilin.null_test.adapter.DummyContent;
import com.example.amoxicilin.null_test.adapter.MyItemRecyclerViewAdapter;


public class CommunicationFragment extends Fragment {

    private int mColumnCount = 1;
    private OnListFragmentInteractionListener mListener;
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
                             Bundle savedInstanceState) {
        View rootview=inflater.inflate(R.layout.fragment_comunication,container, false);

        if (rootview instanceof RecyclerView) {
            Context context = rootview.getContext();
            RecyclerView recyclerView = (RecyclerView) rootview;
            if (mColumnCount <= 1) {
                recyclerView.setLayoutManager(new LinearLayoutManager(context));
            } else {
                recyclerView.setLayoutManager(new GridLayoutManager(context, mColumnCount));
            }
            recyclerView.setAdapter(new MyItemRecyclerViewAdapter(DummyContent.ITEMS, mListener));
        }
        RecyclerView recyclerView = (RecyclerView)rootview.findViewById(R.id.id_recyclerview);

        return rootview;
    }

    public interface OnListFragmentInteractionListener {

        void onListFragmentInteraction(DummyContent.DummyItem item);
    }
}









布局文件：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context="com.example.amoxicilin.null_test.CommunicationFragment">

    <SearchView
        android:id="@+id/search"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="#F0F0F0F0" >
    </SearchView>

    <android.support.v7.widget.RecyclerView
        android:id="@+id/id_recyclerview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        app:layoutManager="LinearLayoutManager"
        android:dividerHeight="10dp"
        android:padding="10dp"
        android:scrollbarStyle="outsideOverlay"
        tools:listitem="@layout/item_com" />


</LinearLayout>



求前辈们指点指点