在recyclerview中选择cardview也会选择其他项目

Question

当我更改在recyclerview内部的cardview的颜色时，它也会改变其他项目的颜色。我该如何解决这个问题。

以下是我要更改背景颜色的模块部分：

    public RecyclerItemClickListener(Context context, final RecyclerView recyclerView, OnItemClickListener listener) {

        mListener = listener;

        mGestureDetector = new GestureDetector(context, new GestureDetector.SimpleOnGestureListener() {
            @Override
            public boolean onSingleTapUp(MotionEvent e) {
                return true;
            }

            @Override
            public void onLongPress(MotionEvent e) {
                View child = recyclerView.findChildViewUnder(e.getX(), e.getY());
                if (child != null && mListener != null) {
                    mListener.onLongItemClick(child, recyclerView.getChildAdapterPosition(child));
                    int position = recyclerView.getChildLayoutPosition(child);
                    child.setBackgroundColor(mContext.getResources().getColor(R.color.blue_light));
                    Toast.makeText(mContext, "Id " + String.valueOf(position), Toast.LENGTH_SHORT).show();
                    deleteItems.add(position);
                }
            }
        });
    }

适配器的代码如下：

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

List <DiaryInfo> mItems;
SQLiteDatabase mydatabase;

public DiaryAdapter() {
    super();
    mItems = new ArrayList <DiaryInfo> ();
    mItems = MainActivity.diaryinfo;
}

@Override
public ViewHolder onCreateViewHolder(ViewGroup viewGroup, int i) {
    View v = LayoutInflater.from(viewGroup.getContext())
            .inflate(R.layout.content_main, viewGroup, false);
    ViewHolder viewHolder = new ViewHolder(v);

    mydatabase = (MainActivity.mContext).openOrCreateDatabase("remember", android.content.Context.MODE_PRIVATE, null);

    // While changing database information here change at Itemadd's done button listener also!
    mydatabase.execSQL("CREATE TABLE IF NOT EXISTS memories_pics(id VARCHAR PRIMARY KEY, path VARCHAR)");

    return viewHolder;
}

@Override
public void onBindViewHolder(ViewHolder viewHolder, int i) {
    try {
        DiaryInfo info = mItems.get(i);
        viewHolder.desc.setText(Html.fromHtml((info.getDesc()).replaceAll("''", "\"")));

        // Modifying date to readable format

        String tempDate = info.getDate();
        Locale locale = (MainActivity.mContext).getResources().getConfiguration().locale;
        String[] temp = tempDate.split("/"); // Splitting date dd/mm/yyyy
        int month = Integer.valueOf(temp[1]);
        DateFormatSymbols symbols = new DateFormatSymbols(locale);
        String[] monthNames = symbols.getMonths();
        String currentMonth = monthNames[month - 1];
        viewHolder.date.setText(currentMonth + " " + temp[0]);

        String id = info.getThumbnail();
        String path = ""; // Final path of the thumbnail

        Cursor cursor = mydatabase.rawQuery("SELECT * FROM memories_pics WHERE id=\'" + id + "\' LIMIT 1", null);
        if (cursor.moveToFirst()) {
            while (cursor.isAfterLast() == false) {
                path = cursor.getString(cursor
                        .getColumnIndex("path"));
                cursor.moveToNext();
                break;
            }
        }
        cursor.close();

        File file = null;

        // Either load image from user clicked images or a default image

        if ((String.valueOf(path.split("=")[0])).equals("")) {
            Glide.with(MainActivity.mContext).load(R.drawable.default_pic).centerCrop().into(viewHolder.imgThumbnail);
        } else {
            file = new File(String.valueOf(path.split("=")[0])); // Load path in file
            Glide.with(MainActivity.mContext).load(file).centerCrop().into(viewHolder.imgThumbnail);
        }
    }

    catch (Exception e) {

    }
}

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

public Object getItem(int pos) { return mItems.get(pos); }

class ViewHolder extends RecyclerView.ViewHolder {

    public ImageView imgThumbnail;
    public TextView date, desc;

    public ViewHolder(View itemView) {
        super(itemView);
        imgThumbnail = (ImageView) itemView.findViewById(R.id.thumbnail);
        date = (TextView)itemView.findViewById(R.id.date);
        desc = (TextView)itemView.findViewById(R.id.description);
    }
}
}

以下是cardview布局：

<RelativeLayout
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <ImageView
        android:id="@+id/thumbnail"
        android:layout_width="match_parent"
        android:layout_height="150dp"
        android:layout_alignParentTop="true"
        android:scaleType="centerCrop"
        android:src="@drawable/default_pic"/>

    <TextView
        android:id="@+id/date"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/thumbnail"
        android:maxLines="1"
        android:padding="4dp"
        android:text="Title"
        android:textColor="#222"
        android:textStyle="bold"
        android:textSize="22sp"/>

    <TextView
        android:id="@+id/description"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_below="@+id/date"
        android:maxLines="3"
        android:padding="4dp"
        android:text="Description"
        android:textColor="#666"
        android:textSize="14sp"
        android:ellipsize="end"/>

</RelativeLayout>

请帮忙！