Problem to implement a QThread

Hello!

I am having a problem to implement a QThread. My application crash when the thread is started - processo->start()

Help me please. Thanks a lot.

Code below:

Code:

---

//defconexao.cpp
#include "defconexao.h"
#include "ui_defconexao.h"
#include "limpalayout.h"
#include "caixadialogos.h"
#include "verificaos.h"
#include "caixamensagens.h"
#include "criaconfservidor.h"
 
#include <QCoreApplication>
#include <QProgressBar>
 
#include <QDebug>
 
defConexao::defConexao(QWidget *parent) :
    QDialog(parent),
    ui(new Ui::defConexao)
{
    ui->setupUi(this);
 
    verticalLayout_3 = new QVBoxLayout;
    limparLayout = new limpaLayout;
    this->ui->verticalLayout->addLayout(verticalLayout_3);
}
 
defConexao::~defConexao()
{
    delete ui;
}
 
void defConexao::on_cancelarButton_clicked()
{
    this->close();
}
 
void defConexao::on_tipoConexaoComboBox_currentIndexChanged(int index)
{
    if(index == 0)
    {
        limparLayout->limpaWidgetLayout(this->verticalLayout_3, false);
        ui->okButton->setEnabled(false);
    }
    else
    {
        if(index == 1)
        {
            limparLayout->limpaWidgetLayout(this->verticalLayout_3, false);
 
            horizontalLayout_2 = new QHBoxLayout;
 
            avisoConfigExisteLabel = new QLabel("<font color=\"red\">Utilize esta opção apenas se o arquivo de configuração<br/>já existir");
            avisoConfigExisteLabel->setAlignment(Qt::AlignHCenter);
 
            caminhoArquivoLineEdit = new QLineEdit();
            caminhoArquivoLineEdit->setReadOnly(true);
            selecionaArquivoButton = new QPushButton("Selecione o arquivo", this);
 
            this->horizontalLayout_2->addWidget(caminhoArquivoLineEdit);
            this->horizontalLayout_2->addWidget(selecionaArquivoButton);
 
            this->verticalLayout_3->addWidget(avisoConfigExisteLabel);
            this->verticalLayout_3->addLayout(horizontalLayout_2);
 
            barraProgresso = new QProgressBar;
            this->verticalLayout_3->addWidget(barraProgresso);
 
            ui->okButton->setEnabled(true);
 
            connect(selecionaArquivoButton, SIGNAL(clicked()), this, SLOT(on_selecionaArquivoButton_clicked()));
        }
        else
        {
            if(index == 2)
            {
                limparLayout->limpaWidgetLayout(this->verticalLayout_3, false);
 
                codigoIdBdLabel = new QLabel("Código de identificação do banco de dados");
                codigoIdBdLineEdit = new QLineEdit();
 
                this->verticalLayout_3->addWidget(codigoIdBdLabel);
                this->verticalLayout_3->addWidget(codigoIdBdLineEdit);
 
                barraProgresso = new QProgressBar;
                this->verticalLayout_3->addWidget(barraProgresso);
 
                ui->okButton->setEnabled(true);
            }
            else
            {
                if(index == 3)
                {
                    limparLayout->limpaWidgetLayout(this->verticalLayout_3, false);
 
                    horizontalLayout_2 = new QHBoxLayout;
 
                    verticalLayout_4 = new QVBoxLayout;
                    verticalLayout_5 = new QVBoxLayout;
 
                    enderecodBdLabel = new QLabel("IP ou HOST do banco de dados");
                    enderecoBdLineEdit = new QLineEdit();
 
                    portaBdLabel = new QLabel("Porta");
                    portaBdLineEdit = new QLineEdit();
                    portaBdLineEdit->setText("5432");
                    portaBdLineEdit->setMaximumWidth(70);
                    portaBdLineEdit->setValidator(new QIntValidator(this));
 
                    this->verticalLayout_4->addWidget(enderecodBdLabel);
                    this->verticalLayout_4->addWidget(enderecoBdLineEdit);
 
                    this->verticalLayout_5->addWidget(portaBdLabel);
                    this->verticalLayout_5->addWidget(portaBdLineEdit);
 
                    this->horizontalLayout_2->addLayout(verticalLayout_4);
                    this->horizontalLayout_2->addLayout(verticalLayout_5);
 
                    this->verticalLayout_3->addLayout(horizontalLayout_2);
 
                    barraProgresso = new QProgressBar;
                    this->verticalLayout_3->addWidget(barraProgresso);
 
                    ui->okButton->setEnabled(true);
                }
            }
        }
    }
}
 
void defConexao::on_selecionaArquivoButton_clicked()
{
    //this->caminhoArquivoLineEdit->setText(caixaDeDialogos->abrirArquivo("Arquivo de configuração do banco de dados","Todos os arquivos (*.*);;Arquivo XML (*.xml)"));
    this->caminhoArquivoLineEdit->setText(caixaDeDialogos->abrirArquivo("Arquivo de configuração do banco de dados","Arquivo XML (*.xml)"));
}
 
void defConexao::on_okButton_clicked()
{
    if(ui->tipoConexaoComboBox->currentIndex() == 1)
    {
        if(this->caminhoArquivoLineEdit->text() == "")
        {
            this->caminhoArquivoLineEdit->setStyleSheet("border: 1px solid red");
        }
        else
        {
            this->caminhoArquivoLineEdit->setStyleSheet("");
 
        }
    }
    else
    {
        if(ui->tipoConexaoComboBox->currentIndex() == 2)
        {
            if(this->codigoIdBdLineEdit->text() == "")
            {
                this->codigoIdBdLineEdit->setStyleSheet("border: 1px solid red");
            }
            else
            {
                this->codigoIdBdLineEdit->setStyleSheet("");
 
            }
        }
        else
        {
            bool camposCompletos = true;
            if(ui->tipoConexaoComboBox->currentIndex() == 3)
            {
                if(this->enderecoBdLineEdit->text() == "")
                {
                    camposCompletos = false;
                    this->enderecoBdLineEdit->setStyleSheet("border: 1px solid red");
                }
                else
                {
                    this->enderecoBdLineEdit->setStyleSheet("");
                }
 
                if(this->portaBdLineEdit->text() == "")
                {
                    camposCompletos = false;
                    this->portaBdLineEdit->setStyleSheet("border: 1px solid red");
                }
                else
                {
                    this->portaBdLineEdit->setStyleSheet("");
                }
 
                if(camposCompletos == true)
                {
                    QThread processo;
                    criaConfServidor *criaConf = new criaConfServidor;
                    criaConf->connectaThreadComSlot(processo);
                    criaConf->moveToThread(&processo);
                    //processo.start();
                }
            }
        }
    }
}

---

Code:

---

//defconexao.h
#ifndef DEFCONEXAO_H
#define DEFCONEXAO_H
 
#include "limpalayout.h"
#include "caixadialogos.h"
#include "criaconfservidor.h"
 
#include <QDialog>
#include <QLabel>
#include <QLineEdit>
#include <QLayout>
#include <QProgressBar>
 
namespace Ui {
class defConexao;
}
 
class defConexao : public QDialog
{
    Q_OBJECT
 
public:
    explicit defConexao(QWidget *parent = 0);
    ~defConexao();
 
    bool verificaArquivoExiste();
    //void criaArquivoConfCloud(QString codigo);
    //void criaArquivoConfServidor();
    //void verificaArquivoEstrutura(QString caminho);
 
private slots:
    void on_cancelarButton_clicked();
    void on_tipoConexaoComboBox_currentIndexChanged(int index);
    void on_selecionaArquivoButton_clicked();
    void on_okButton_clicked();
 
private:
    Ui::defConexao *ui;
 
    QLabel *codigoIdBdLabel;
    QLineEdit *codigoIdBdLineEdit;
 
    QLabel *enderecodBdLabel;
    QLineEdit *enderecoBdLineEdit;
    QLabel *portaBdLabel;
    QLineEdit *portaBdLineEdit;
 
    QLabel *avisoConfigExisteLabel;
    QLineEdit *caminhoArquivoLineEdit;
    QPushButton *selecionaArquivoButton;
 
    QVBoxLayout *verticalLayout_3;
    QVBoxLayout *verticalLayout_4;
    QVBoxLayout *verticalLayout_5;
    QHBoxLayout *horizontalLayout_2;
 
    QProgressBar *barraProgresso;
 
    limpaLayout *limparLayout;
 
    caixaDialogos *caixaDeDialogos;
};
 
#endif // DEFCONEXAO_H

---

Code:

---

//criaconfservidor.cpp
#include "criaconfservidor.h"
//#include "bancodados.h"
 
//#include <QSql>
//#include <QSqlDatabase>
//#include <QDebug>
 
criaConfServidor::criaConfServidor(QObject *parent) :
    QObject(parent)
{
}
 
void criaConfServidor::connectaThreadComSlot(QThread &processo)
{
    qDebug() << "Conexão efetuada";
    connect(&processo, SIGNAL(started()), this, SLOT(criaArquivoConf()));
}
 
void criaConfServidor::criaArquivoConf()
{
    qDebug() << "Entrou";
}

---

Code:

---

//criaconfservidor.h
#ifndef CRIACONFSERVIDOR_H
#define CRIACONFSERVIDOR_H
 
#include <QObject>
#include <QThread>
#include <QDebug>
 
class criaConfServidor : public QObject
{
    Q_OBJECT
public:
    //explicit criaConfServidor(QObject *parent = 0, QString DBHost = "192.168.0.1", QString DBPorta = "5432");
    explicit criaConfServidor(QObject *parent = 0);
    void connectaThreadComSlot(QThread &processo);
 
signals:
 
public slots:
    void criaArquivoConf();
 
};
 
#endif // CRIACONFSERVIDOR_H

---

You destroy the thread object after starting it, i.e. the variable "processo" goes out of scope.

Cheers,
_

If your program is crashing at "//processo.start();", I'd say it's because your QThread processo; is local and goes out of scope. Try making it global.

So, where it must be declared?

Somewhere that gives it a lifetime longer than the function. Either a member variable of the class or allocate the QProcess object on the heap remembering to arrange deletion at the appropriate time.

It worked. Thank you very much people. I created the Qthread in .h file and iniciated it in .cpp file.