JColourChooser  JColourChooser

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The JDisplay Java Applet displays the large program listings on this web page. JDisplay requires an up-to-date browser and Java version 1.5+, preferably 1.7.0_04. If you can’t see the listings, or if you just want to learn more about JDisplay, click  here for help.

This essay does not describe an existing computer program, just one that should exist. This essay is about a suggested student project in Java programming. This essay gives a rough overview of how it might work. I have no source, object, specifications, file layouts or anything else useful to implementing this project.

This project outline is not like the artificial, tidy little problems you are spoon-fed in school, when all the facts you need are included, nothing extraneous is mentioned, the answer is fully specified, along with hints to nudge you toward a single expected canonical solution. This project is much more like the real world of messy problems where it is up to you to fully the define the end point, or a series of ever more difficult versions of this project, and research the information yourself to solve them.

Everything I have to say to help you with this project is written below. I am not prepared to help you implement it; or give you any additional materials. I have too many other projects of my own.

Though I am a programmer, I don’t do people’s homework for them. That just robs them of an education.

You have my full permission to implement this project in any way you please and to keep all the profits from your endeavour.

Please do not email me about this project without reading the disclaimer above.

The JDisplay (Java Display) Java Applet displays the large program listings on this web page. JDisplay requires Java version 1.5 or later, preferably 1.6.0_12. If you can’t see the listings, or if you just want to learn more about JDisplay, click here for help.
This project is fairly easy, just tedious since the UI (User Interface) has so many widgets and so many minor interactions between them. The intent of the project is to create a replacement for Sun’s JColorChooser.

Here is a mockup of what the new JColourChooser might look like. It gets you perhaps 80% of the way there.

Sorry, you need Java 1.5 or later to run this Applet.

If, JColourChooser, the above Color chooser Java Applet (that can also be run as an application) does not work…

  1. If Copy/Paste (Ctrl-C/Ctrl-V) do not work, you can turn them back on by modifying your java.policy file. This is not for the novice or faint of heart. instructions Your alternative is to download this program and run it without a browser.
  2. Often problems can be fixed simply by clicking the reload button on your browser.
  3. Make sure you have both JavaScript and Java enabled in your browser.
  4. This Java Applet (that can also be run as an application) needs 32-bit (not 64-bit) Java 1.5 or later. For best results use the latest 1.7.0_04. If you have both 32 and 64-bit JVMs installed, in the Java Control Panel, configure your 32-bit java.exe as the user JVM and your 64-bit java.exe as the system JVM. You also need a recent browser.
  5. It works under any operating system that supports Java e.g. W2K/XP/W2003/Vista/W7-32/W7-64/Linux/Ubuntu/Solaris/OSX
  6. You should see the Applet hybrid above looking much like this screenshot. If you don’t, the following hints should help you get it working:
  7. Especially if this Applet hybrid has worked before, try clearing the browser cache and rebooting.
  8. To ensure your Java is up to date, check with Wassup. First, download it and run it as an application independent of your browser, then run it online as an Applet to add the complication of your browser.
  9. If the above Applet hybrid does not work, check the Java console for error messages.
  10. If the above Applet hybrid does not work, you might have better luck with the downloadable version available below.
  11. If you are using Mac OS X and would like an improved Look and Feel, download the QuaQua look & feel from randelshofer.ch/quaqua. UnZip the contained quaqua.jar and install it in ~/Library/Java/Extensions or one of the other ext dirs.
  12. If you are using Microsoft Internet Explorer 7, 8 or 9, try another browser. Seriously. Microsoft has taken great pains, over and over, to screw up Java and every other multi-platform standardisation.
  13. If you are using Microsoft Internet Explorer 7, 8 or 9, you must click to allow blocked content permission for Active X to run. This also gives permission to Java to run. Click the Information bar, and then click Allow blocked content. Unfortunately, this also allows dangerous ActiveX code to run. However, you must do this in order to get access to perfectly-safe Java Applets running in a sandbox. This is part of Microsoft’s war on Java. Don’t put up with it! Use a different browser.
  14. If you are using Microsoft Internet Explorer 9, makes sure the Java Plug-In SSV helper add-in is installed and enabled. If it is not, try reinstalling the Java JRE.
  15. If you have Windows 7 64-bit and Internet Explorer 64-bit, in theory you can use 64-bit Java, but I never been able to get it to work.
  16. Try upgrading to a more recent version of your browser, or try a different browser e.g. Firefox, SeaMonkey, Safari or Avant.
  17. If you still can’t get the program working click HELP for more detail.
  18. If you can’t get the above Applet hybrid working after trying the advice above and from the HELP button below, have bugs to report or ideas to improve the program or its documentation, please send me an email atemail Roedy Green.
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How does it differ from Sun’s JColorChooser?

Hints On Implementation

Since there are so many widgets, the code will become very repetitive, i.e. error prone. The trick is to use arrays of Components, e.g. index [0] for background and [1] for foreground. That way you can use common code for background and foreground. Similarly index R G B components as [0] [1] [2]. and H S B as [0] [1] [2].

For slower machines, you might want to configure some of the updates to happen only after the slider stops moving rather than continuously.

Check out how JColorChooser works and the colour chooser in FontShowerAWT.

Here is the code I used to create this mockup:

view

Learning More

Oracle’s Javadoc on JColorChooser class : available:
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