Qt QObject: connnect()函数不能连接

I have the code like this:

我有这样的代码:

class MyListView : public QListView
{
public:
    MyListView();
    ~MyListView();

public slots:
    void insertData();
    void deleteData();
    void showData();

private:
    QStringListModel *model;
    QListView *listView;
};
class M