Re: New Swing Window Not Drawn

From:

Tom Hawtin <usenet@tackline.plus.com>

Newsgroups:

comp.lang.java.programmer

Date:

Mon, 22 Jan 2007 22:14:59 +0000

Message-ID:

<45b536a9$0$8715$ed2619ec@ptn-nntp-reader02.plus.net>

Hal Vaughan wrote:

public void activate() {
        //flagActive is set to false when the window should disappear
        flagActive = true;
        new Thread(new Runnable() {
                public void run() {
                        System.out.println("-----Opening Wait Window.");
                        //jSelf is the JFrame class for the window
                        jSelf.setVisible(true);
                        while (true) {
                                try {Thread.sleep(50);} catch (Exception e) {
                                        System.out.println("Insomnia");
                                }
                                if (!flagActive) break;
                        }
                        System.out.println("-----Closing Wait Window.");
                        jSelf.setVisible(false);
                }
        }).start();
        return;
}

Write out a million time "I shall not use Swing components on the Event
Dispatch Thread (EDT)."

It should be simple enough to update the visible state using a bit of
EventQueue.invokeLater:

     private volatile active;
     public void setActive(boolean active) {
         //flagActive is set to false when the window should disappear
         this.active = active;
         java.awt.Event.invokeLater(new Runnable() { public void run() {
                         //jSelf is the JFrame class for the window
                         jSelf.setVisible(MyOuterClass.this.active);
         }});
     }

For experts: Use javax.swing.Timer to prevent the frame flashing on and
off for very short bouts of activity. Technically javax.swing.Timer
should be called on the EDT (within the invokeLater).

Tom Hawtin