Why aren't my QRadioButtons appearing in my QGroupBox? - c++

Question

Here is my code, it's super simple:
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QGroupBox>
#include <QRadioButton>
#include <QVBoxLayout>
MainWindow::MainWindow(QWidget *parent) :
QMainWindow(parent),
ui(new Ui::MainWindow)
{
ui->setupUi(this);
QGroupBox* genderGroupBox = new QGroupBox("Gender", ui->centralWidget);
QVBoxLayout* genderGroupBoxLayout = new QVBoxLayout(genderGroupBox);
QRadioButton* maleRadioButton = new QRadioButton("Male", genderGroupBox);
QRadioButton* femaleRadioButton = new QRadioButton("Female", genderGroupBox);
genderGroupBoxLayout->addStretch();
}
but for some reason my program looks like this:
I've programmed in Qt quite a bit and I am totally baffled as to why the radio buttons aren't showing up inside the group box. I've tried explicitly adding them with
genderGroupBoxLayout->addWidget(maleRadioButton);
and manually adding the layout via
genderGroupBox->setLayout(genderGroupBoxLayout);
even though neither should be necessary because of how they were constructed. It looks like the radio buttons don't have any parent at all.
Anyone have any ideas?
I'm coding using Qt Creator 3.1.2 on a mac. Also the .ui file is empty of everything except centralWidget, which has a grid layout.

Answer 1

Please refer to the documentation :
When you use a layout, you do not need to pass a parent when
constructing the child widgets. The layout will automatically reparent
the widgets (using QWidget::setParent()) so that they are children of
the widget on which the layout is installed.
Your code should look like the following :
QGroupBox* genderGroupBox = new QGroupBox("Gender");
QVBoxLayout* genderGroupBoxLayout = new QVBoxLayout;
QRadioButton* maleRadioButton = new QRadioButton("Male");
QRadioButton* femaleRadioButton = new QRadioButton("Female");
genderGroupBoxLayout->addWidget(maleRadioButton);
genderGroupBoxLayout->addWidget(femaleRadioButton);
genderGroupBoxLayout->addStretch();
genderGroupBox->setLayout(genderGroupBoxLayout);
ui->centralWidget->layout()->addWidget(genderGroupBox);