error: type 'QObject' is not a direct base of 'MyThread'

[deleted286]

I have an error on the

MyThread::MyThread(QObject* parent)
   : QObject(parent) ///Here is an error 
{
   
}

Could someone tell me where I've gone wrong - thanks!

mythread.cpp

#include "mythread.h"
#include "mainwindow.h"
#include <QtCore>
#include <QDebug>
#include <QFile>
#include <QTimer>
#include <QThread>
#include <QMutex>
#include <QQueue>
#include <QMessageBox>
#include <QApplication>
#include <QtWidgets/QApplication>
#include <QtWidgets/QMainWindow>
#include <QFileDialog>
#include <QMainWindow>

MyThread::MyThread(QObject* parent)
    : QObject(parent)
{
    
}

MyThread::~MyThread() {

}

void MyThread::writeData()
{

....
    emit writingDone();
}


void MyThread::run()  //Reading file from txt with thread1
{
    ...
}

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QtWidgets/QMainWindow>
#include <QMainWindow>

MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
{
    ui->setupUi(this);

    // Initialize the new objects
    myThreadObject = new MyThread();
    myQThread = new QThread();

    // Move to new thread
    myThreadObject->moveToThread(myQThread);

    // connect signal and slots
    connect(this, &MainWindow::startWriting, myThreadObject, &MyThread::writeData);
    connect(myThreadObject, &MyThread::writingDone, this, &MainWindow::writingDoneByThread);

    // Start the new thread
    myQThread->start();
}

[Christian Ehrlicher]

'QObject' is not a direct base of 'MyThread'

And what do you don't understand here? The message explicitly tells you what's wrong. MyThread doesn't directly derive from QObject...

[JonB]

@suslucoder
Show your declaration of class MyThread in mythread.h.

[deleted286]

@JonB

#define MYTHREAD_H
#include <QtCore>
#include <QMainWindow>
#include <QObject>
#include <QWidget>
#include <QQueue>
#include <QMutex>

class MyThread: public QThread
{
    Q_OBJECT

public:
    MyThread(QObject* parent =nullptr);
    ~MyThread();

signals:
    void writingDone(); //signal for main thread

public slots:
    void writeData(); // this slot ask the thread to write data

    void run();


private:
    QQueue<double> queue;
};

#endif // MYTHREAD_H

[Christian Ehrlicher]

@suslucoder said in error: type 'QObject' is not a direct base of 'MyThread':

class MyThread: public QThread

Exactly what the error message told you...
No need to derive from QThread here at all btw.

[deleted286]

@Christian-Ehrlicher Im trying to do subclass QObject. I can read also the error. Obviously I'm doing something wrong. Do you think is it the true way you make me realize my mistake?

[Christian Ehrlicher]

@suslucoder said in error: type 'QObject' is not a direct base of 'MyThread':

Im trying to do subclass QObject

But you don't:

class MyThread: public QThread

[JonB]

@suslucoder
Can I ask you one thing: are you trying to use threads because this is an assignment/exam/educational? Do you really have any need for using threads, for whatever you are trying to achieve? Threads are one of the hardest things to get right. So many beginners on this forum start out trying to use threads when there is no need to do so, and run into problems, it could be a bad idea and not at all needed. If I were learning Qt they are the last thing I would want to start out on. Unless you have a good reason for really wanting to use them.

[deleted286]

@JonB It is not an assignment or an exam. I just want to learn all subjects quickly

[Christian Ehrlicher]

@suslucoder said in error: type 'QObject' is not a direct base of 'MyThread':

I just want to learn all subjects quickly

Then I would start with the basics and not with advanced topics like threads.

[deleted286]

@Christian-Ehrlicher thank you, i understand my mistake and solve it.