c++ - QT C++ 在关闭应用程序时防止运行时错误

Question

我正在编写一个 QT 应用程序，构建和工作一切正常，但是当我关闭一个正在运行的线程的应用程序时，该应用程序关闭并显示一条消息: [运行时错误....]。

应用程序输出显示:

QThread: Destroyed while thread is still running
The program has unexpectedly finished.
The process was ended forcefully.
example crashed.

如何解决？

例子:

main.cpp

#include "mainwindow.h"
#include <QApplication>
#include <QString>

int main(int argc, char *argv[])
{
    QApplication a(argc, argv);
    MainWindow w;
    w.show();

    return a.exec();
}

主窗口.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
    example = new Thread(this);
    connect(example, SIGNAL(print_line(QString)), this, SLOT(print_line2(QString)), Qt::BlockingQueuedConnection);
}

MainWindow::~MainWindow()
{
    delete ui;
}
void MainWindow::print_line2(QString in)
{
    ui->textBrowser->append(in);
}

void MainWindow::on_pushButton_clicked()
{
    example->start();
}

主窗口.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H

#include <QMainWindow>
#include <Thread.h>

namespace Ui {
class MainWindow;
}

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    explicit MainWindow(QWidget *parent = 0);
    ~MainWindow();
    Thread *example;

public slots:
    void print_line2(QString in);

private slots:

    void on_pushButton_clicked();

private:
    Ui::MainWindow *ui;
};

#endif // MAINWINDOW_H

线程.cpp

#include "Thread.h"
#include <windows.h>

using namespace std;

Thread::Thread(QObject *parent):
    QThread(parent)
{

}

Thread::~QThread()
{
    delete ui;
}

void Thread::print(QString in)
{
    print_line(in);
}

void Thread::run()
{
    int count = 0;
    for(;;) {
        Sleep(100);
        count += 1;
        print(QString::number(count));
    }
}

线程.h

#ifndef READINFO_H
#define READINFO_H
#include <QThread>

class Thread : public QThread
{
    Q_OBJECT

public:
   explicit Thread(QObject *parent =0);
   void print(QString in);
   void run();

signals:

   void print_line(QString x);

};

#endif

Ready example

Answer 1

问题在于，当您的应用程序关闭时，线程仍处于运行状态。

Thread::Run() 中的代码包含一个无限循环——它无法自行终止。您需要编写您的线程，以便它退出，或者至少，您需要在您的应用程序关闭之前强行终止该线程。

要强制终止，您可以像这样向 MainWindow 析构函数添加两行代码:

MainWindow::~MainWindow() 
{ 
    example->terminate(); 
    example->wait(); 
    (...)
}