Question

我想从带有QT的文件中读取一些数据，然后通过QComboBox在QTableWidget中显示数据。

void DemoDataView::on_comboBox_activated(const QString &arg1)
{
    ui->tableWidget->setColumnCount(5);
    ui->tableWidget->setRowCount(21);
    ui->tableWidget->verticalHeader()->setVisible(false);
    ui->tableWidget->setHorizontalHeaderLabels(QString("Age Range ; Male Population ; Male Percentage ; Female Population ; Female Percentage").split(";"));
    ui->tableWidget->resizeColumnsToContents();
    ui->tableWidget->resizeRowsToContents();

QFile inputFile("./data.txt");

if(!inputFile.open(QIODevice::ReadOnly))
{
    QMessageBox::information(0, "Error", inputFile.errorString());
}

QTextStream in(&inputFile);
int rows = 0;

while(!in.atEnd()) {

    QString mLine = in.readLine();
    QStringList fields = mLine.split(" ");
    QStringList::iterator it = fields.begin();
    QString regName = *it;

    ui->label->setText(arg1);

    if(regName != "<END>" && QString::compare(regName, arg1) == 0) {
        ui->label->setText(regName);
        it++;
        QString ageRange = *it;
        it++;
        QString nMale = *it;
        double male = nMale.toDouble();
        it++;
        QString nFemale = *it;
        double female = nFemale.toDouble();
        ui->tableWidget->setItem(rows, 0, new QTableWidgetItem(ageRange));
        ui->tableWidget->setItem(rows, 1, new QTableWidgetItem(nMale));
        ui->tableWidget->setItem(rows, 3, new QTableWidgetItem(nFemale));
        ui->tableWidget->setItem(rows, 2, new QTableWidgetItem(malePercCalc(male, female)));
        ui->tableWidget->setItem(rows, 4, new QTableWidgetItem(femalePercCalc(male, female)));

        rows++;

    }

inputFile.close();

    }
}

该文件位于项目文件夹和构建项目文件夹中。当我运行应用程序时，一切正常，但在“应用程序输出”选项卡中，我有以下错误消息：

＆＃34; QIODevice :: read（QFile，＆＃34; ./ data.txt＆＃34;）：设备未打开＆＃34;

每次点击QComboBox项目。

如果它有用，这是QComboBox的填充代码：

void DemoDataView::setComboBoxRegion() {

QFile inputFile("./data.txt");

if(!inputFile.open(QIODevice::ReadOnly))
{
    QMessageBox::information(0, "Error", inputFile.errorString());
}

QTextStream in(&inputFile);

while(!in.atEnd()) {

    QString mLine = in.readLine();
    QStringList fields = mLine.split(" ");


    QStringList::iterator it = fields.begin();
    QString regName = *it;

    if(regName != "<END>") {
        if(ui->comboBox->findText(regName) == -1){
            ui->comboBox->addItem(regName);
        }
    }
}

inputFile.close();
}

Answer 1

你的问题是你在打电话：

inputFile.close();

循环的INSIDE，这意味着它在第一个循环中关闭。我无法想到任何可能发生这种事情的情况;

要解决此问题，您应将其移至循环的外部。

尝试从QFile读取时出错

1 个答案: