dolphin wrote:

Xiaochuan Fang wrote:

Michael Rauscher schrieb:

Yes.

And exposes the fact that Swing only allows one single Java Event Dispatch
Thread (EDT) that you have to use when you interact with the GUI.

-- Lew

Yes, it is.

Swing is based on AWT. The main difference between AWT and Swing is that
Swing paints components (and manage their states) by itself while AWT
let the native system paint them.

Consequences:

1. Swing is a tick slower than AWT.
2. Swing isn't thread-safe.
3. It's easier to produce Swing apps that aren't responsive.

ad 1) It's just a tick, so it's far away from being "too slow".

ad 2) As a result there's the single-thread rule:
      Swing components can be accessed by only one thread at a time.

      Note, that there are no guarantees that AWT is thread-safe.
      It's a result of the underlying system.

ad 3) One can easily block the EDT - in both, Swing and AWT.
      It's just that one can recognize a blocked EDT in a Swing
      application immediately.

      Let's compare what happens if one blocks the EDT in Swing
      and AWT. To do this, we'll have a look at a GUI containing
      one button that - if pressed - blocks the EDT for about
      5 seconds.[1]

      Swing: the button keeps pressed for 5 seconds.
             In fact, the whole content of that window will not
             get repainted within the 5 seconds.

      AWT:   the button returns to the normal state immediately.

      So, how can one recognize a blocked EDT in a AWT app?

      Resize the Window while the EDT is blocked. Both, the Swing
      and the AWT app will not resize the button until
      the 5 seconds are over.

      In real apps one can't continue until the EDT is not blocked
      anymore - in both, Swing and AWT.

Bye
Michael

[1] Sample application (negative), to call use
    java SwingAWT [mode]

    If mode is not given, the Swing version will run.
    If mode is swing, the Swing version will run.
    If mode is anything other, the AWT version will run.

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class SwingAWT {
    private ActionListener listener = new ActionListener() {
        public void actionPerformed( ActionEvent e ) {
            try {
                Thread.sleep(5000);
            } catch ( InterruptedException ie ) {}
        }
    };

    private Frame frame;
    private Component button;

    private void initAWT() {
        button = new Button("Block EDT");
        ((Button)button).addActionListener( listener );
        frame = new Frame("SwingAWT - AWT");
    }

    private void initSwing() {
        button = new JButton("Block EDT");
        ((JButton)button).addActionListener( listener );
        frame = new JFrame("SwingAWT - Swing");
    }

    public void createAndShowGUI( boolean awt ) {
        if ( awt )
            initAWT();
        else
            initSwing();

        frame.addWindowListener( new WindowAdapter() {
            public void windowClosing( WindowEvent e ) {
                frame.dispose();
            }
        });
        frame.add( button );
        frame.pack();
        frame.setVisible(true);
    }

    public static final void main( String args[] ) {
        final boolean awt =
                (args.length < 1 || "swing".equals(args[0])) ?
                false : true;

        EventQueue.invokeLater( new Runnable() {
            public void run() {
                new SwingAWT().createAndShowGUI(awt);
            }
        });
    }
}

In my opinion a Swing application needn't be /too/ slow but it may take
an experienced Swing developer to achieve that result. For example many
people would have trouble displaying a 100MB text document in Swing.
However with a careful choice of Document implementation this can
perform very well -- you can use the normal JTextArea to handle all the
display details, all the bottlenecks were in the Document implementation
(some of these have been fixed since I last experimented).

Mark Thornton

In the same way SWT, my PC and internet connections are too slow. Your
point is nearly always true for nearly anything.

I already mentioned that Swing is a tick slower than AWT and of course
it would be nice if Swing would get faster.

NB: A few years ago I tried both NetBeans and Eclipse under Linux. A
situation where SWT was much slower than Swing. But I would say that
neither SWT nor Swing is too slow.

Bye
Michael

Hi Chris,

Ah, but many do! Speaking as one who came away with a bruised/broken coccyx
after jumping off Richmond Bridge two summers ago (the day before it reached
100F) I can testify that it's still not a pleasant experience :-) I didn't
hit the bottom even though the tide was way out and, as a local, I should've
known better, it was just the sheer majesty and height of that 45ft leap and
tsunami-inducing entry that did the damage. But then there's that Viles
disease, hacked up bodies in suitcases, numerous discharges from Iselworth
treatment works, and the seemingly endless detritus that most of London
seems to deposit in it, and only an idiot would jump in! That's alcohol for
ya :-(

Anyway WRT Swing -vs- AWT, as a beginner I've been using AWT 'cos I thought
it was a simpler yet still functional interface. Is that wrong? Did Swing
supplant AWT? Is there a library better than Swing? I imagine technology
hasn't stood still since the gridbag layout, but where should one invest
there time? Does anyone handcraft this stuff anymore or is it all generated
code now anyway?

Regards Richard Maher