qt错误:对' vtable for Thread'的未定义引用

I have the code:

我的代码:

#include <iostream>
#include <QThread>
#include <unistd.h>
#include <stdlib.h>
#include <QApplication>


using std::cerr;
using std::endl;

class Thread : public QThread
{
    Q_OBJECT
public:
    Thread();
    ~Thread();
    void setMessage(const QString &_message);
    void stop();
protected:
    void run();
private:
    QString message;
    volatile bool stopped;
};

Thread::Thread()
{
    stopped = false;    
    run();
}

Thread::~Thread()
{

}


void Thread::run()
{
    while(!stopped){
        cerr << qPrintable(message);
        sleep(1);
    }
        stopped = false;
        cerr << endl;
}

void Thread::stop()
{
    stopped = true; 
}

void Thread::setMessage(const QString &_message)
{
    message = _message; 
}

int main(int argc,char *argv[])
{
    QApplication app(argc, argv);
    Thread *A,*B;
    A = new Thread();
    B = new Thread();
    A->setMessage("Thread A\n");
    B->setMessage("Thread B\n");
//.run();
//.run();
    sleep(10);
    A->stop();
    B->stop();
    return 0;
}
#include <iostream>