Re: Frustrated by AWT..need some help

From:
jt <jtlinux1@yahoo.ca>
Newsgroups:
comp.lang.java.help
Date:
Fri, 01 Jun 2007 15:57:45 -0300
Message-ID:
<46606c47$0$4067$9a566e8b@news.aliant.net>
Andrew Thompson wrote:

printdude1968@gmail.com wrote:

..much easier once you have a firmer foundation in the fundamentals.


Very much agree.

...After poking around Swing, I am wondering if it is possible
to create a very simple
panel with 3 circles that can be filled with different colors. Using
Matisse (as little as I have)


This code was not written in Matisse, but I have
every confidence that Matisse can use normal
J2SE layouts, so it should be possible to write
this code* (using J2SE layouts) using Matisse

* Or some functional equivalent.

<sscce>
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;

class TrafficLight {

  public static void main(String[] args) {
    JFrame f = new JFrame("Lights");
    JPanel lightboard = new JPanel( new GridLayout(0,1) );

    lightboard.add( new TrafficSignal(Color.green) );
    lightboard.add( new TrafficSignal(Color.yellow) );
    lightboard.add( new TrafficSignal(Color.red) );

    f.setContentPane( lightboard );
    f.pack();
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.setLocationRelativeTo(null);
    f.setVisible(true);
  }
}

class TrafficSignal extends JPanel {

  Color on;
  int radius = 75;
  int border = 10;
  boolean active;

  TrafficSignal(Color color) {
    on = color;
    active = true;
    this.addMouseListener( new MouseAdapter() {
      public void mouseClicked(MouseEvent me) {
        active = !active;
        repaint();
      }
    } );
  }

  public Dimension getPreferredSize() {
    int size = (radius+border)*2;
    return new Dimension( size, size );
  }

  public void paintComponent(Graphics g) {
    g.setColor( Color.black );
    g.fillRect(0,0,getWidth(),getHeight());

    if (active) {
      g.setColor( on );
    } else {
      g.setColor( on.darker().darker().darker() );
    }
    g.fillOval( border,border,2*radius,2*radius );
  }
}
</sscce>

leads me to believe that my requirements are too simple for swing.


I do not think you are very clear on the differences
between Swing and AWT yet, and the replies to
this thread have done little to help.

Most of the events and layouts used in Swing or
AWT based GUI Development, come from the AWT.
AWT also encompasses anything to do with Graphics,
Images, Colors, D'n'D, printing, Geometry and a slew of
other things. The major difference is in the set of *GUI*
components offered by each.

A GUI developer truly needs a solid understanding of
many of the AWT packages and classes before they
can effectively code Swing GUIs.

The first code example posted, made my skin crawl.
It was horrific. It not only had an odd disparity to the title
(it as using Swing JApplet and JFrame in a thread title
'..AWT..') but also stumbled (probably by accident) upon
the one Swing class for which overriding paint() is the
correct way to do Swing painting. Then there was the
odd mixture of an applet and frame.. Applets should
be avoided in simple examples, and the combined
applet/application is a more 'advanced' use of applets.
Then painting directly to the root component, in preference
to creating each signal as a separate object (ick!). ...

I won't go on - it's too painful, and my code - that you
all can rip apart and criticise, is above.

I'm sure there is a way to do what I want in Swing
but the GUI builder doesn't have any simple shapes or ways to fill
them that I can see.


Custom components in a layout.

...I guess I'll find out more
as I make my way further in the tutorial.


Way to go.


Hey, Andrew! I finally got around to trying your code out (I've spent
the day rebuilding two feisty fawn boxes) and I'm impressed. I even
understand most of it :-) One question though, what if I want to use a
method of some sort to do the same thing the mouseListener is doing?
The goal of my project is to be able to turn the lights off and on using
a command sent based on a timing routine. I was thinking something like
toggleLight(Light greenLight)

What this method would do is simulate pressing the green light.

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