Question

I have a normal widget application which should show a finite automata in a graphic view widget. I add a QGgraphicsView to the main window, which has an instance of QGraphicsScene:

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    scene(new QGraphicsScene(this))
{
    setupUi(this);
    scene->addText("Hello");
    ui->graphicsView->setScene(scene); // bumb!
}

Program crashes by a segmentation fault when it tries to set scene for graphicsView.

Answer 1

You should choose between inheriting from the ui class and having a ui member.

Then the code should be either:

ui->setupUi(this);
...
ui->graphicsView->setScene(scene);

or:

setupUi(this);
...
graphicsView->setScene(scene);