使用片段实例制作GridView

Question

我想实现GridView，每个单元格都包含一个类对象。为此，我实现了片段类：

public class DayUC extends Fragment {

    /*
    some variables
    */

    // use to create instance of class with initial parameters
    public static DayUC newInstance(//initial parameters) {
        DayUC dayUC = new DayUC();
        /*
        set parameters
        */
        return dayUC;
    }

    @Override
    public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
        rootView = inflater.inflate(R.layout.fragment_layout, container, false);
        initialization()       //initial variables and view elemans (textView, ...)
        return rootView;
    }
}

我也创建了GridViewAdapter：

public class GridViewAdapter extends BaseAdapter {

    private ArrayList<DayUC> gridList;      //list of grid DayUC objects
    Context context;

    public GridViewAdapter(Context context, ArrayList<DayUC> gridList) {
        this.gridList = gridList;
        this.context = context;
    }

    @Override
    public int getCount() {
        return gridList.size();
    }

    @Override
    public DayUC getItem(int position) {
        return gridList.get(position);
    }

    @Override
    public long getItemId(int position) {
        return position;
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {
        return gridList.get(position).getView();
    }
}

但是当我创建GridView时，它会抛出NullPointerException！我发现在gridView元素（DayUC）中 onCreateView（）从未调用过。所以 gridList.get（position）.getView（）返回null !!

有谁可以帮我解决这个问题？我怎么能强制 onCreateView 被调用？

修改：添加了MainActivity onCreate方法：

protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        DayUC[] dayUC = new DayUC[42];

        monthGridView = (GridView) findViewById(R.id.month_view);

        for (int i = 0; i < 42; i++) {
            dayUC[i] = DayUC.newInstance(//inpute arguments)
            dayUCList.add(dayUC[i]);
            monthCal.add(Calendar.DATE, 1);
        }

        gridViewAdapter = new MonthGridViewAdapter(getActivity(), dayUCList);
        monthGridView.setAdapter(gridViewAdapter);
        gridViewAdapter.notifyDataSetChanged();
    }