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Re: Could this be done better

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In article <87zjbg97c5.fsf@Equus.decebal.nl>, Cecil Westerhof 
(Cecil@decebal.nl) says...

> I was just wondering if this could be done better. Especially
> ?updateColour?. First I did not removed the text, but then I could see
> the colour changing before the text was changed. This way I find more
> pleasing and I do not notice that the text disappears.
> 
>     import java.awt.*;
>     import java.util.*;
> 
>     import javax.swing.*;
> 
>     @SuppressWarnings("serial")
>     public class ColourCycling extends JFrame {

First lesseon: Never derive from JFrame, always derive views from JPanel 
and put that into a frame.
Reason: You may want use this component elsewhere (inside another panel 
probably).

>         // public functions
>         public ColourCycling() {
>             java.util.Timer colourTimer = new java.util.Timer();
> 
>             getContentPane().setBackground(background);
>             setLayout(new GridBagLayout());
>             label.setFont(new Font("serif", Font.BOLD, 25));
>             add(label);
>             pack(); 

Lesson two: pack() is useless, if you set the rame size manually, after 
packing:

>             setSize(getWidth(), 3 * getHeight());

Lesson three: Never set the size of the frame directly. pack(9 should be 
enough.
The frame size is the size of the frame including its decorations. 
Different systems have thicker frames, smaller or larger fonts in the 
frame title. If you set the size directly, you might cut off the bottom 
or right part of the content,if the frame decorations are larger than 
expected, or you leave space, if it is smaller.
You want the frame to wrap around a panel, let the layout manager figure 
out the site of the content. If realy necessary, set the preferredSize 
of a component. Use pack() after you have built your component hierarchy 
and leave the frame size alone.

>             label.setBackground(background);
>             updateColour(getCurrentColour());
>             colourTimer.schedule(new SwitchColour(), delay, delay);
>             setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
>             setTitle(description);
>             setVisible(true);
>         }
> 
>         public static void main(String[] args) {
>             new ColourCycling();
>         }

Lesson four. Never create or manipulatre Components outside of the Event 
Dispatching Thread.
You want:
EvenQueue.invokeLater(new Runnable(){
 public void run(){
  JFrame frame = new JFrame();
  frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
  frame.getContentpane().add(new ColourCycling());//assume CC ext JPanel
  frame.pack();
  frame.setVisible(true);
 }
});



 
>         // private classes
>         private class Colour {


Lesson five: Naming a private class the same as an API class works, but 
is not well readable. Find a better name, for example 
"ColorWithDescription" or "NamedColor" or "ChoosableColor" or whatever 
is appropriate for its use.

>             // public
>             public Colour(Color color, String description) {
>                 this.color          = color;
>                 this.description    = description;
>             }
//...

> 
>         private class SwitchColour extends TimerTask {
>             public void run() {
>                 updateColour(getNextColour());
>             }
>         }

Back to lesson four: Never create or manipulate Components outside of 
the Event Dispatching Thread. "invokeLater" is your friend:

Since the TimerTask is executed by a java.util.Timer, it is executed on 
e thread other than the Swing Event Dispatching Thread, where everything 
has to be rendered. You want to push the operation to the event 
dispatching thread:

EventQueue.invokeLater(new Runnable(){
 public void run(){
  updateColour(getNextColour());
 }
});

By the way: It doesn't matter, if you use "EventQueue.invokeLater" or 
"SwingUtilities.invokeLater". 

Kind regards,
Wanja


-- 
..Alesi's problem was that the back of the car was jumping up and down 
dangerously - and I can assure you from having been teammate to 
Jean Alesi and knowing what kind of cars that he can pull up with, 
when Jean Alesi says that a car is dangerous - it is. [Jonathan Palmer]

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Thread

Could this be done better Cecil Westerhof <Cecil@decebal.nl> - 2014-11-24 12:16 +0100
  Re: Could this be done better "Qu0ll" <Qu0llSixFour@gmail.com> - 2014-11-24 22:49 +1100
    Re: Could this be done better Cecil Westerhof <Cecil@decebal.nl> - 2014-11-24 17:54 +0100
      Re: Could this be done better Knute Johnson <eternal@knutejohnson.com> - 2014-11-24 09:37 -0800
        Re: Could this be done better Cecil Westerhof <Cecil@decebal.nl> - 2014-11-24 19:27 +0100
  Re: Could this be done better Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-24 09:23 -0500
    Re: Could this be done better Cecil Westerhof <Cecil@decebal.nl> - 2014-11-24 17:45 +0100
      Re: Could this be done better Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-24 13:42 -0500
        Re: Could this be done better Cecil Westerhof <Cecil@decebal.nl> - 2014-11-25 00:12 +0100
    Re: Could this be done better Knute Johnson <eternal@knutejohnson.com> - 2014-11-24 09:19 -0800
      Re: Could this be done better Knute Johnson <eternal@knutejohnson.com> - 2014-11-24 09:41 -0800
        Re: Could this be done better Cecil Westerhof <Cecil@decebal.nl> - 2014-11-25 00:55 +0100
      Re: Could this be done better Cecil Westerhof <Cecil@decebal.nl> - 2014-11-25 00:11 +0100
        Re: Could this be done better Knute Johnson <eternal@knutejohnson.com> - 2014-11-24 16:26 -0800
  Re: Could this be done better Brixomatic <brixomatic@yahoo.com> - 2014-11-25 19:58 +0100
    Re: Could this be done better Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-25 14:36 -0500
      Re: Could this be done better Brixomatic <brixomatic@yahoo.com> - 2014-11-26 01:58 +0100
        Re: Could this be done better Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-26 08:48 -0500
          Re: Could this be done better Brixomatic <brixomatic@yahoo.com> - 2014-11-29 19:43 +0100
            Re: Could this be done better Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-29 15:44 -0500
              Re: Could this be done better Eric Sosman <esosman@comcast-dot-net.invalid> - 2014-11-29 15:47 -0500

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