qt在文件中选择新建文件不会显示信息

Question

    fileCreateAction=new QAction(tr("新建文件"),this);
    fileCreateAction->setShortcut(tr("Ctrl+o"));
    fileCreateAction->setStatusTip(tr("新建一个文件"));
    connect(fileCreateAction,SIGNAL(triggered(bool)),this,SLOT(fileCreateActionSlot()));

####为什么这里面的东西不会显示在界面

    void MainWindow::fileCreateActionSlot()
{

        QLineEdit *line_edit=new QLineEdit();
        line_edit->setGeometry(50,50,80,80);
        line_edit->setText("文件名");
        QLabel my_label;
        my_label.setText("啊啊啊啊");

}