Qt无法手动连接到任何插槽（UI编辑器）

Question

I am learning to use Qt.

For easier programming I use the UI-Editor.

THE PROBLEM

When I want to connect my QTreeWidget, It suddenly doesn't want to do anything.

I don't want to connect it via UI-Editor, because I (later on) want to implement my own slot, which doesn't get recognized by the compiler (ERROR MESSAGE: didnt find slot ... in file ui_mainwindow.h , although the slot is defined in mainwindow.cpp and declared in mainwindo.h)

So this is my connection code:

MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{

    //connects all the objects with the needed slots
     QObject::connect(ui->treeWidget, &QTreeWidget::clicked, QApplication::quit);


     ui->setupUi(this);
}

BUT: When I click on any of the items of QTreeWidget, it doesn't quit out of the programm.

I am absolutely sure it's a QTreeWidget and not a QTreeView, I also use the Linux (-->GNOME) version of Qt 5.7

Also, I don't get any warnings/compiler errors.

Because I am a newb to Qt, I might have overseen a simple error, in this case, sorry :P

Answer 1

Actually, there is no quit() slot in QWidget or its descendant QMainWindow .

You should use QCoreApplication::quit() instead.

---

Below, qApp refers to the QApplication instance:

Qt 4 syntax:

QObject::connect(ui->treeWidget, SIGNAL(clicked(QModelIndex)), qApp, SLOT(quit()));

Qt 5 syntax:

QObject::connect(ui->treeWidget, &QTreeWidget::clicked, QCoreApplication::quit);

or

QObject::connect(ui->treeWidget, &QTreeWidget::clicked, []{ QCoreApplication::quit(); });

---

Update

Found the issue. Check the main.cpp file, you are creating the QMainWindow instance instead of MainWindow . That is why your derived class constructor isn't even called.