为什么程序出错

一壶浊酒l

#ifndef QUERY_H
#define QUERY_H

#include <QDialog>
#include <QFile>
#include <QList>
#include <QString>


namespace Ui {
class Query;
}

class Query : public QDialog
{
    Q_OBJECT

public:
    explicit Query(QWidget *parent = 0);
    int readfromfile();
     ~Query();



private:
    Ui::Query *ui;

    //QList<QString>stu_lines;  //就是这里！！！！
};

#endif // QUERY_H

如图标记的注释行，我注释后就可以运行不然就会提示程序出错如下面；

Starting D:\QT workplace\build-StudentManager-Desktop_Qt_5_9_2_MinGW_32bit-Debug\debug\StudentManager.exe...
程序异常结束。
The process was ended forcefully.
D:\QT workplace\build-StudentManager-Desktop_Qt_5_9_2_MinGW_32bit-Debug\debug\StudentManager.exe crashed.

这是为什么啊??加上这句就报错