widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QDebug>
#include <QThread>

class QPushButton;

namespace Ui {
class Widget;
}

class myObject : public QObject
{
    Q_OBJECT
public:
    myObject() {}
    ~myObject() {}

public slots:
    void first() 
    {
        qDebug()<< QThread::currentThreadId();
    }
    void second() 
    {
        qDebug()<< QThread::currentThreadId();
    }
    void third() 
    {
        qDebug()<< QThread::currentThreadId();
    }
};

class Widget : public QWidget
{
    Q_OBJECT
    
public:
    explicit Widget(QWidget *parent = 0);
    ~Widget();
    
private:
    Ui::Widget *ui;
    myObject *my;
    QPushButton *firstButton,*secondButton,*thirdButton,*selfButton;

public slots:
    void onFirstPushed();
    void onSelfPushed();
};

#endif // WIDGET_H
 

#include "widget.h"
#include "ui_widget.h"
#include <QVBoxLayout>
#include <QPushButton>


Widget::Widget(QWidget *parent) :
    QWidget(parent),
    ui(new Ui::Widget)
{
    ui->setupUi(this);
    my = new myObject;
    firstButton = new QPushButton(tr("firstBtn"), 0);
    connect(firstButton, SIGNAL(clicked()), this, SLOT(onFirstPushed()));
    secondButton = new QPushButton(tr("secondBtn"), 0);
    connect(secondButton, SIGNAL(clicked()), my, SLOT(second()), Qt::DirectConnection);
    thirdButton = new QPushButton(tr("thirdBtn"), 0);
    connect(thirdButton, SIGNAL(clicked()), my, SLOT(third()), Qt::QueuedConnection);
    selfButton = new QPushButton(tr("selfBtn"), 0);
    connect(selfButton, SIGNAL(clicked()), this, SLOT(onSelfPushed()));

    QVBoxLayout *layout = new QVBoxLayout;
    layout->addWidget(firstButton);
    layout->addWidget(secondButton);
    layout->addWidget(thirdButton);
    layout->addWidget(selfButton);

    this->setLayout(layout);

    QThread *thread = new QThread;
    my->moveToThread(thread);
    connect(thread, SIGNAL(started()), my, SLOT(first()));
    thread->start();
}

Widget::~Widget()
{
    delete ui;
}

void Widget::onFirstPushed() 
{
    my->first();
}

void Widget::onSelfPushed() 
{
    qDebug() << QThread::currentThreadId();
}