Mainwindow is empty without any widgets.

[houmingc]

When i build and run, the mainwindow is empty without any widgets.
But i have created all the component in the mainwindow constructor.
why they never appear?
@
-----------------MainWindow constructor------------
ui->setupUi(this);
brightnessLabel= new QLabel(tr("Brightness :"));
brightnessName= new QLineEdit;
brightnessLabel->setBuddy(brightnessName);

contrastLabel= new QLabel(tr("Brightness :"));
contrastName= new QLineEdit;
contrastLabel->setBuddy(contrastName);

volumeLabel= new QLabel(tr("Brightness :"));
volumeName= new QLineEdit;
volumeLabel->setBuddy(volumeName);

OutputsourceLabel= new QLabel(tr("Brightness :"));
OutputsourceName= new QLineEdit;
OutputsourceLabel->setBuddy(OutputsourceName);

DownloadLabel= new QLabel(tr("Brightness :"));
DownloadName= new QLineEdit;
DownloadLabel->setBuddy(DownloadName);

QHBoxLayout *layout =new QHBoxLayout;
layout->addWidget(brightnessLabel);
layout->addWidget(brightnessName);

----------------------main------------------------
QApplication a(argc, argv);
MainWindow w;
w.show();

@

[andreyc]

You have not assigned the layout to MainWindow.

[houmingc]

How to assign ?

[Moschops]

QMainWindow inherits a setlayout function.

http://doc.qt.io/qt-5/qwidget.html#setLayout

[SGaist]

Hi,

You can't change the layout of a QMainWindow. What you would do is create a main/container widget and set it as central widget.