Realize the function of students filling out their applications on qt

void Application::apply()
{
    if(ui->comboBox->currentText() == "")
        QMessageBox::warning(this, "Waring", "Please choose your major", QMessageBox::Yes, QMessageBox::Yes);
    else
    {
        QStringList info;
        info << ui->lineEdit->text() << ui->lineEdit_2->text() << ui->lineEdit_3->text()
             << ui->comboBox->currentText() << ui->lineEdit_4->text();
        emit sendData(info);
        this->close();
    }
}