Ruby`requiret'：无法加载这样的文件（LoadError）(Ruby `require': cannot load such file (LoadError))

 试试这个代码，这只是一个由Recycler Adapter支持的List Activity，包含List Activity的XML，Card Layout XML文件 
 
   public class ListActivity extends AppCompatActivity {

   DBHelper helper;
  static List<DBModel>dbList;
   RecyclerView mRecyclerView;
   private static RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_list);

    addListenerOnButtonAdd();
    TextView tvNoData = (TextView)findViewById(R.id.tvNoData);

    setTitle("");// This sets the title of the toolbar
    Toolbar topToolBar = (Toolbar)findViewById(R.id.toolbar);
    setSupportActionBar(topToolBar);
    //topToolBar.setLogo(R.drawable.keyss);// See Notes in MainActivity

    setRequestedOrientation( ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);


    helper = new DBHelper(this);
    dbList = new ArrayList<>();
    dbList = helper.getDataFromDB();

    mRecyclerView = (RecyclerView)findViewById(R.id.recycleview);
    mRecyclerView.setHasFixedSize(true);

    // use a linear layout manager
    mLayoutManager = new LinearLayoutManager(this);
    mRecyclerView.setLayoutManager(mLayoutManager);

    // Code below defines the adapter
    mAdapter = new RecyclerAdapter(this,dbList);
    mRecyclerView.setAdapter(mAdapter);

    int sz = dbList.size();
    if(sz == 0){
        tvNoData.setVisibility(View.VISIBLE);
        tvNoData.setText("No Data");
    }
  }

  // This method is called from DetailsActivity and notifies Recycler View 
  that the DB was changed

   of DB and Recycler View
   public static void removeListRow(int position) {
    dbList.remove(position);
    mAdapter.notifyItemRemoved(position);
    mAdapter.notifyItemRangeChanged(position, dbList.size());
   }

    /* this BUTTON is on the ToolBar click to ADD new record */
    private void addListenerOnButtonAdd() {
    // Navigate to DetailsActivity to ADD new DATA
    Toolbar tb = (Toolbar) findViewById( R.id.toolbar );
    setSupportActionBar( tb );

    tb.findViewById( R.id.btnAdd ).setOnClickListener( new 
    View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intentSP = new Intent(ListActivity.this, 
   DetailsActivity.class );
            Bundle extras = new Bundle();
            extras.putString("FROM_LIST_ACTIVITY","true" );
            intentSP.putExtras(extras);
            startActivity( intentSP );
        }
    } );
 }

public void onBackPressed(){
    Intent intent = new Intent( ListActivity.this, MainActivity.class );
    startActivity( intent );
 }
 }


   <?xml version="1.0" encoding="utf-8"?>
  <LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:id="@+id/activity_list"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
  android:background="@color/color_lightGray"
   android:orientation="vertical"
   tools:context="com.searchdb.ListActivity">

    <android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    android:minHeight="?attr/actionBarSize"
    android:background="@color/color_darkGray"
    android:layout_width="match_parent"
    android:layout_height="64dp">

    <ImageView
        android:id="@+id/imageTB"
        android:layout_width="70dp"
        android:layout_height="wrap_content"
        android:paddingBottom="2dp"
        android:paddingLeft="2dp"
        android:paddingRight="2dp"
        android:paddingTop="4dp"
        android:src="@drawable/keyss" />

    <TextView
        android:text="@string/list_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/toolbar"
        android:layout_alignParentStart="true"
        android:layout_marginStart="30dp"
        android:layout_marginBottom="20dp"
        android:id="@+id/tvLA"
        android:textStyle="bold"
        android:textColor="@color/color_White"
        android:textSize="22sp" />

    <Button
        android:text="@string/add"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btnAdd"
        android:layout_marginLeft="100dp"
        android:textSize="18sp"
        android:textStyle="bold"
        android:focusable="false"
        android:textColor="@color/color_White"
        android:background="@color/color_Transparent"/>

  </android.support.v7.widget.Toolbar>

  <LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycleview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:text="TextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tvNoData"
        android:gravity="center"
        android:layout_marginTop="240dp"
        android:visibility="invisible"
        android:textAllCaps="true"
        android:textStyle="bold"
        android:textSize="30sp"
        android:textColor="@color/color_Red" />
 </LinearLayout>

  </LinearLayout>

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

  static List<DBModel> dbList;
  static private Context context;
   int sz;

   RecyclerAdapter(Context context, List<DBModel> dbList) {

    RecyclerAdapter.dbList = new ArrayList<>();
    RecyclerAdapter.context = context;
    RecyclerAdapter.dbList = dbList;
 }

 @Override
 public RecyclerAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int 
 viewType) {

    View itemLayoutView = 
 LayoutInflater.from(parent.getContext()).inflate(R.layout.item_row, null);
    // create ViewHolder
    ViewHolder viewHolder = new ViewHolder(itemLayoutView);

    return viewHolder;
}

@Override
public void onBindViewHolder(RecyclerAdapter.ViewHolder holder, int 
 position) {
    holder.rowid.setText(String.valueOf(dbList.get(position).getRowid()));
    holder.station.setText(dbList.get(position).getStation_Name());
    System.out.println("RecyclerAdapter BindViewHolder FIRST position 
 "+position);
}

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

 public class ViewHolder extends RecyclerView.ViewHolder implements 
 View.OnClickListener {

    public TextView station, rowid;

    public ViewHolder(View itemLayoutView) {
        super(itemLayoutView);

        rowid = (TextView) itemLayoutView.findViewById(R.id.rvROWID);
        station = (TextView) itemLayoutView.findViewById(R.id.rvSTATION);
        // Attach a click listener to the entire row view
        itemLayoutView.setOnClickListener(this);

    }

   @Override 
    public void onClick(View v) {

       Intent intentN = new Intent(context, DetailsActivity.class);
       Bundle extras = new Bundle();
       extras.putInt("POSITION", getAdapterPosition());
       extras.putString("FROM_LIST_ACTIVITY", "false");
       intentN.putExtras(extras);
       context.startActivity(intentN);
   }
   }
   }

  <?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="match_parent"
  android:layout_margin="5dp"
  android:orientation="horizontal"
  card_view:cardCornerRadius="5dp"
  card_view:cardUseCompatPadding="true">

   <RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/color_White">

    <TextView
        android:id="@+id/rvROWID"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:gravity="left|center_vertical"
        android:padding="10dp"
        android:textAlignment="center"
        android:text="Position ID"
        android:textColor="@color/color_Black"
        android:layout_marginLeft="10dp"
        android:textStyle="bold"
        android:textSize="16sp"/>

    <TextView
        android:id="@+id/rvSTATION"
        android:layout_width="fill_parent"
        android:layout_height="50dp"
        android:padding="10dp"
        android:gravity="right|center_vertical"
        android:text="Station"
        android:layout_marginLeft="10dp"
        android:textStyle="bold"
        android:textSize="16sp"
        android:textColor="@color/color_Black" />

   </RelativeLayout>

  </android.support.v7.widget.CardView>

Try this code this is just a List Activity that is backed by a Recycler Adapter the XML for the List Activity is included and the Card Layout XML file 
 
   public class ListActivity extends AppCompatActivity {

   DBHelper helper;
  static List<DBModel>dbList;
   RecyclerView mRecyclerView;
   private static RecyclerView.Adapter mAdapter;
    private RecyclerView.LayoutManager mLayoutManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_list);

    addListenerOnButtonAdd();
    TextView tvNoData = (TextView)findViewById(R.id.tvNoData);

    setTitle("");// This sets the title of the toolbar
    Toolbar topToolBar = (Toolbar)findViewById(R.id.toolbar);
    setSupportActionBar(topToolBar);
    //topToolBar.setLogo(R.drawable.keyss);// See Notes in MainActivity

    setRequestedOrientation( ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);


    helper = new DBHelper(this);
    dbList = new ArrayList<>();
    dbList = helper.getDataFromDB();

    mRecyclerView = (RecyclerView)findViewById(R.id.recycleview);
    mRecyclerView.setHasFixedSize(true);

    // use a linear layout manager
    mLayoutManager = new LinearLayoutManager(this);
    mRecyclerView.setLayoutManager(mLayoutManager);

    // Code below defines the adapter
    mAdapter = new RecyclerAdapter(this,dbList);
    mRecyclerView.setAdapter(mAdapter);

    int sz = dbList.size();
    if(sz == 0){
        tvNoData.setVisibility(View.VISIBLE);
        tvNoData.setText("No Data");
    }
  }

  // This method is called from DetailsActivity and notifies Recycler View 
  that the DB was changed

   of DB and Recycler View
   public static void removeListRow(int position) {
    dbList.remove(position);
    mAdapter.notifyItemRemoved(position);
    mAdapter.notifyItemRangeChanged(position, dbList.size());
   }

    /* this BUTTON is on the ToolBar click to ADD new record */
    private void addListenerOnButtonAdd() {
    // Navigate to DetailsActivity to ADD new DATA
    Toolbar tb = (Toolbar) findViewById( R.id.toolbar );
    setSupportActionBar( tb );

    tb.findViewById( R.id.btnAdd ).setOnClickListener( new 
    View.OnClickListener() {
        @Override
        public void onClick(View v) {
            Intent intentSP = new Intent(ListActivity.this, 
   DetailsActivity.class );
            Bundle extras = new Bundle();
            extras.putString("FROM_LIST_ACTIVITY","true" );
            intentSP.putExtras(extras);
            startActivity( intentSP );
        }
    } );
 }

public void onBackPressed(){
    Intent intent = new Intent( ListActivity.this, MainActivity.class );
    startActivity( intent );
 }
 }


   <?xml version="1.0" encoding="utf-8"?>
  <LinearLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools"
   android:id="@+id/activity_list"
   android:layout_width="match_parent"
   android:layout_height="match_parent"
  android:background="@color/color_lightGray"
   android:orientation="vertical"
   tools:context="com.searchdb.ListActivity">

    <android.support.v7.widget.Toolbar
    android:id="@+id/toolbar"
    android:minHeight="?attr/actionBarSize"
    android:background="@color/color_darkGray"
    android:layout_width="match_parent"
    android:layout_height="64dp">

    <ImageView
        android:id="@+id/imageTB"
        android:layout_width="70dp"
        android:layout_height="wrap_content"
        android:paddingBottom="2dp"
        android:paddingLeft="2dp"
        android:paddingRight="2dp"
        android:paddingTop="4dp"
        android:src="@drawable/keyss" />

    <TextView
        android:text="@string/list_view"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/toolbar"
        android:layout_alignParentStart="true"
        android:layout_marginStart="30dp"
        android:layout_marginBottom="20dp"
        android:id="@+id/tvLA"
        android:textStyle="bold"
        android:textColor="@color/color_White"
        android:textSize="22sp" />

    <Button
        android:text="@string/add"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:id="@+id/btnAdd"
        android:layout_marginLeft="100dp"
        android:textSize="18sp"
        android:textStyle="bold"
        android:focusable="false"
        android:textColor="@color/color_White"
        android:background="@color/color_Transparent"/>

  </android.support.v7.widget.Toolbar>

  <LinearLayout
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <android.support.v7.widget.RecyclerView
        android:id="@+id/recycleview"
        android:layout_width="match_parent"
        android:layout_height="match_parent"/>

</LinearLayout>

<LinearLayout
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:text="TextView"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:id="@+id/tvNoData"
        android:gravity="center"
        android:layout_marginTop="240dp"
        android:visibility="invisible"
        android:textAllCaps="true"
        android:textStyle="bold"
        android:textSize="30sp"
        android:textColor="@color/color_Red" />
 </LinearLayout>

  </LinearLayout>

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

  static List<DBModel> dbList;
  static private Context context;
   int sz;

   RecyclerAdapter(Context context, List<DBModel> dbList) {

    RecyclerAdapter.dbList = new ArrayList<>();
    RecyclerAdapter.context = context;
    RecyclerAdapter.dbList = dbList;
 }

 @Override
 public RecyclerAdapter.ViewHolder onCreateViewHolder(ViewGroup parent, int 
 viewType) {

    View itemLayoutView = 
 LayoutInflater.from(parent.getContext()).inflate(R.layout.item_row, null);
    // create ViewHolder
    ViewHolder viewHolder = new ViewHolder(itemLayoutView);

    return viewHolder;
}

@Override
public void onBindViewHolder(RecyclerAdapter.ViewHolder holder, int 
 position) {
    holder.rowid.setText(String.valueOf(dbList.get(position).getRowid()));
    holder.station.setText(dbList.get(position).getStation_Name());
    System.out.println("RecyclerAdapter BindViewHolder FIRST position 
 "+position);
}

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

 public class ViewHolder extends RecyclerView.ViewHolder implements 
 View.OnClickListener {

    public TextView station, rowid;

    public ViewHolder(View itemLayoutView) {
        super(itemLayoutView);

        rowid = (TextView) itemLayoutView.findViewById(R.id.rvROWID);
        station = (TextView) itemLayoutView.findViewById(R.id.rvSTATION);
        // Attach a click listener to the entire row view
        itemLayoutView.setOnClickListener(this);

    }

   @Override 
    public void onClick(View v) {

       Intent intentN = new Intent(context, DetailsActivity.class);
       Bundle extras = new Bundle();
       extras.putInt("POSITION", getAdapterPosition());
       extras.putString("FROM_LIST_ACTIVITY", "false");
       intentN.putExtras(extras);
       context.startActivity(intentN);
   }
   }
   }

  <?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="match_parent"
  android:layout_margin="5dp"
  android:orientation="horizontal"
  card_view:cardCornerRadius="5dp"
  card_view:cardUseCompatPadding="true">

   <RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/color_White">

    <TextView
        android:id="@+id/rvROWID"
        android:layout_width="wrap_content"
        android:layout_height="50dp"
        android:gravity="left|center_vertical"
        android:padding="10dp"
        android:textAlignment="center"
        android:text="Position ID"
        android:textColor="@color/color_Black"
        android:layout_marginLeft="10dp"
        android:textStyle="bold"
        android:textSize="16sp"/>

    <TextView
        android:id="@+id/rvSTATION"
        android:layout_width="fill_parent"
        android:layout_height="50dp"
        android:padding="10dp"
        android:gravity="right|center_vertical"
        android:text="Station"
        android:layout_marginLeft="10dp"
        android:textStyle="bold"
        android:textSize="16sp"
        android:textColor="@color/color_Black" />

   </RelativeLayout>

  </android.support.v7.widget.CardView>