swing VS QT

Qt vs. Swing

 QtSwing
Class name Qxxxx Jxxxx
Writing the "GUI" class Assume the following class declaration GUI.h 
    #include <qmainwindow.h>

    class GUI : public QMainWindow {
       public:
          GUI ();
    }
and the corresponding function definition in GUI.cc 
    GUI::GUI ()
    {
       setWindowTitle ("Simple Qt Window");
    }
The following is written in GUI.java 
    import javax.swing.JFrame;

    public class GUI extends JFrame {
       public GUI ()
       {
          setTitle ("Simple Swing Window");
       }
    }
The main() function 
    #include <qapplication.h>

    int main (int argc, char* argv[]) {
    {
       QApplication myApp(argc, argv);
       GUI myGUI;
       
       myGUI.show();
       return a.exec();
    }
    
    public static void main (String[] args) {
    {
       GUI myGUI = new GUI();
       myGUI.setVisible (true);
    }
Layout Manager 
    GUI::GUI (QWidget *parent, const char *name)
    {
       /* create a vertical box layout for this widget */
       QVBoxLayout *p = new QVBoxLayout ();
       QPushButton *b1 = new QPushButton ("Go");
       QPushButton *b2 = new QPushButton ("Go");
       p->addWidget (b1);
       p->addWidget (b2);
    }
    
    public GUI ()
    {
        JPanel p;
        p = new JPanel();
        /* create a vertical box layout */
        BoxLayout vert = new BoxLayout (contPane, 
           BoxLayout.Y_AXIS);
        p.setLayout (vert);

        JButton b1 = new JButton ("Go");
        JButton b2 = new JButton ("Stop");
        p.add (b1);
        p.add (b2);
    }
Menubar 
    QMenuBar *mb = new QMenuBar (this);      
    setMenuBar (mb);

    QMenu *file = new QMenu (mb);

    QAction *exit = new QAction();
    exit.setText ("Exit");
    file->addAction (exit);
    
    JMenubar mb = new JMenubar();
    setJMenubar (mb);      

    JMenu file = new JMenu ("File");
    mb.add (file);

    JMenuItem exit = new JMenuItem ("Exit");
    file.add (exit);

Event Handling

Swing implements its event handling mechanism via its event and listener objects. Any user action to a GUI component may result in an event object generated and sent to its listener(s).

In Qt, a similar mechanism is implemented via signals and slots. Any user action to a GUI component (Qt widget) may result in a signal "generated" and sent to its associated slot(s). In short:

Swing events are analogous to Qt signals
Swing listeners are analogous to Qt slots

However, Qt signal-slot mechanism is more flexible than Swing event-(event listener) mechanism since Qt allows us to define our own signals.

Swing - JavaQt - C++
Assume the following code segment in Java to handle mouse clicks on a JButton 
    ActionListener myHandler = new MyBtnHandler(); 
    JButton go = new JButton ("Go");
    go.addActionListener (myHandler);
and the class MyBtnHandler: 
    private class MyBtnHandler implements ActionListener
    {
       public void actionPerformed (ActionEvent a)
       {
          /* this method gets called when the go button is clicked */
       }
    }
In Qt, the code is more straight forward: 
    QPushButton *go = new QPushButton ("Go");
    connect (go, SIGNAL(clicked()), this, SLOT(myAction()));
Assuming myAction() is a function in this class (GUI.cc): 
    void GUI::myAction()
    {
        /* this function gets called when the go button is clicked */
    }
In the header file (GUI.h) the function myAction() must be declared as a slot: 
    class GUI : public QWidget {
       // other stuff not shown

       public slots:
          void myAction();

       // other stuff not shown
    }

The Qt online documentation provides a more comprehensive reading materials on signals and slots.

posted on 2015-10-16 22:21  alleyonline  阅读(1398)  评论(0)    收藏  举报

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