image provider

JDisplay Listing Colouriser

The JDisplay Java Applet displays the large program listings on this web page. JDisplay requires an up-to-date browser and Java version 1.8+, preferably 1.8.0_131. If you can’t see the listings, or if you just want to learn more about JDisplay, click  Help Use Firefox for best results.


JDisplay It started out as a way to display Java source code listings in a variety of colours, fonts, sizes and weights to help make them more presentable and readable on a website. Then I expanded it to handle HTML (Hypertext Markup Language), bat, btm, SQL (Standard Query Language), ini, csv and *.properties files. Then I expanded it further the handle mft, sf, mf and http files.

Why would you use it? For the same sorts of reasons you use colours and fonts in an IDE (Integrated Development Environment) like IntelliJ or Eclipse. They make your code much easier to understand for visitors to your website. The techniques used are more much more efficient of bandwidth than displaying images.

There is no server-side code used. Java utilities parse the code snippets into compact binary tokens, assigning colours, fonts, sizes and weights to each token. The tokens are compressed with GZIP and stored in *.ser files. These are not as compact as the original text since they include colourising information for each chunk of text. They are usually more compact that the equivalent formatted HTML, but for very small files they can be bigger because of the serialization overhead of all the fully qualified token class names for the various types of token at the head of the *.ser files. Then the tokens can be rendered three ways:

  1. using a Java Applet. This is usually best for very large listings.
  2. as piece of CSS (Cascading Style Sheets) style-decorated HTML code you include in your html as an iframe. This is usually best for intermediate listings.
  3. inline in your HTML. This is usually best for short listings. The problem, in the process of editing the html it is fairly easy to damage the generated listings. They must be regenerated before every upload.
I have been using the JDisplay suite of utilities for many years. I did not write it for public use. I offer it on an as-is basis. The code itself in well documented, but there is no step-by-step documentation on getting it to work.

I presume the user is familiar with bat and ant files and Java building.

I have not included the enormous HTML static macros package which I use for deciding the sizes and display rendering method for each snippet, though I did include the code to make those decisions hooked into your own framework. At some point in the near future I will make the htmlmacros package available for download separately.

The parsers are rough and ready. They need to work on code snippets and erroneous code, not perfect code the way a standard parser does. If improve the parsers, or add new ones, please pass them along for the public distribution.

JDisplay is enormously more complicated than it appears on the surface. You can spelunk and discover all manner of interesting code you can cannibalise. There are finite state machines, clipregion sensitive Canvas rendering, HTML generators, ObjectStreams…




com.mindprod.compactor compacts html to remove excess white space.
com.mindprod.entities interconvert && etc.
com.mindprod.filter set of FilenameFilters
com.mindprod.htmlmacros part of a large static macros package to expand macros embedded in HTML before the files are uploaded to the server.
com.mindprod.hunkio does IO in big hunks.
com.mindprod.jdisplayaux static macro to decide which of three ways to render a given snippet and inserts the appropriate HTML to do that into your HTML.
com.mindprod.jdisplayorphans detects orphans not referenced by any of your HTML.
com.mindprod.jprep parses the snippets of code, producing binary *.ser files.
com.mindprod.jtokens Tokens and parsers for various languages rendered.
mindprod.css style sheet that controls the fonts/tokens/sizes

Program Flow

  1. Run jprep to parse snippets to binary *.ser files and iframe/*.html files.
  2. Manually decide which of three methods to use and insert the appropriate HTML. (or rig up some code to do this automatically using code in JDisplayAux). To see what the embedded HTML looks like see Java Presenter Student Project which describes how JDisplay works inside. This HTML was generated with static macros. You might do the same, or compose the embedded HTML directly.
  3. Upload to website.
  4. View code inline, as iframe, or via invocation of JDisplay Applet.


  1. Listing expanded inline as HTML with classes for each token. Style sheet mindprod.css controls the colour, font, size and weight. HTML looks like this: The display looks like this:
    Border b1 = BorderFactory.createLineBorder( );
    Border b2 = BorderFactory.createEtchedBorder( EtchedBorder.LOWERED );
    Border b3 = new BevelBorder ( BevelBorder.LOWERED, );
    JPanel panel = new JPanel();
    panel.setBorder( b2 );
  2. Listing using a separate iframe in HTML with classes for each token. Style sheet mindprod.css controls the colour, font, size and weight. The HTML to include an iframe JDisplay looks like this: The display itself looks like this:
  3. Listing using the JDisplay Applet to render a *.ser binary token file. The HTML to invoke an Applet to display the JDisplay binary token *.ser file looks like this: The display itself looks like this: view


Java Requirements and Troubleshooting

JDisplay is a signed Java Applet to Program Listing Display. You are welcome to install it on your own website. If it does not work…
  1. For this Applet to work, you must click grant/accept/always run on this site/I accept the risk to give it permission to let it read the decorated text to display from a file on the server. If you refuse to grant permission, the program may crash with an inscrutable stack dump on the console complaining about AccessController.checkPermission.
  2. In the Java Control Panel security tab, click Start ⇒ Control Panel ⇒ Programs ⇒ Java ⇒ Security, configure medium security to allow self-signed and vanilla unsigned applets to run. If medium is not available, or if Java security is blocking you from running the program, configure high security and add to the Exception Site List at the bottom of the security tab.
  3. Often problems can be fixed simply by clicking the reload button on your browser.
  4. Make sure you have both JavaScript and Java enabled in your browser.
  5. Make sure the Java in your browser is enabled in the security tab of the Java Control panel. Click Start ⇒ Control Panel ⇒ Programs ⇒ Java ⇒ Security ⇒ Enable Java Content in the browser.
  6. This signed Java Applet needs 32-bit or 64-bit Java 1.8 or later. For best results use the latest 1.8.0_131 Java.
  7. You also need a recent browser.
  8. It works under any operating system that supports Java e.g. W2K, XP, W2003, Vista, W2008, W7-32, W7-64, W8-32, W8-64, W2012, W10-32, W10-64, Linux, LinuxARM, LinuxX86, LinuxX64, Ubuntu, Solaris, SolarisSPARC, SolarisSPARC64, SolarisX86, SolarisX64 and OSX
  9. Make sure your zoom is on normal 100% to give the Applet room to run.
  10. You should see the Applet above looking much like this screenshot. If you don’t, the following hints should help you get it working:
  11. Optionally, you may permanently install the Canadian Mind Products code-signing certificate so you don’t have to grant each time.
  12. If the above Applet appears to freeze-up, click Alt-Esc repeatedly to check for any buried permission dialog box.
  13. If you have certificate troubles, check the installed certificates and remove or update any obsolete or suspected defective certificates. The only certificate used by this program is mindprodcert2017rsa.cer.
  14. Especially if this Applet has worked before, try clearing the browser cache and rebooting.
  15. 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.
  16. If the above Applet does not work, check the Java console for error messages.
  17. If the above Applet does not work, you might have better luck with the downloadable version available below.
  18. If you are using Mac OS X and would like an improved Look and Feel, download the QuaQua look & feel from UnZip the contained quaqua.jar and install it in ~/Library/Java/Extensions or one of the other ext dirs.
  19. Upgrade to the latest version of Internet Explorer or another browser.
  20. 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.
  21. Try upgrading to a more recent version of your browser, or try a different browser e.g. Firefox, SeaMonkey, IE or Avant.
  22. If you still can’t get the program working click the red HELP button below for more detail.
  23. If you can’t get the above Applet working after trying the advice above and from the red 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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4.7 2014-08-01 free Java
more infoprecisscreenshotbrowse source repository
for the current version of JDisplay.
Displays Java, HTML, bat, SQL, ini, csv, xml properties… source.
download 4.2MB zip for JDisplay Java source, compiled class files, jar and documentation to run on your own machine as an Applet.

Runs on any OS that supports Java e.g. W2K, XP, W2003, Vista, W2008, W7-32, W7-64, W8-32, W8-64, W2012, W10-32, W10-64, Linux, LinuxARM, LinuxX86, LinuxX64, Ubuntu, Solaris, SolarisSPARC, SolarisSPARC64, SolarisX86, SolarisX64 and OSX.

First install the most recent Java.

To install, extract the zip download with WinZip, (or similar unzip utility) into any directory you please, often J:\ — ticking off the use folder names option.

To check out the corresponding source from the Subversion repository, use the TortoiseSVN repo-browser to
access jdisplay source in repository with [Tortoise] Subversion client on

download ASP PAD XML program description for the current version of JDisplay.

$1989.00 US donated so far. If the CMP utilities solved your problem, please donate a buck or two, or donate to one of the charities featured in the footer public service ads throughout the website and get a tax receipt.

JDisplay is free. Full source included. You may even include the source code, modified or unmodified in free/commercial open source/proprietary programs that you write and distribute. Non-military use only.

Directory Structure

Let’s say your html lives in:


Then the corresponding program listing snippets will live in:


the generated *.ser files live in


and the generated iframe *.html files will live in


All off this must be uploaded to your website.

Resolving Problems

All code should be included with the exception of the htmlmacros package. If you find something missing you can probably download it. In any case, please let me know, so I can include it.

If you have questions, please feel free to ask at email feedback to Roedy Green or Canadian Mind Products. It will help me put together some minimalist documentation. If you are interested in using JDisplay in other contexts (e.g. without htmlmacros), I will be willing to help and write interfacing code at no charge. One PhD student from Germany has used JDisplay to automatically colourise source code listings embedded in Javadoc. He has not yet publicly released the code. I wrote JDisplay originally primarily to demonstrate my vision of the future of what program listings should look like in advanced editors that I call SCIDs. I would love to see JDisplay-like logic in an IDE editor.

downloading JDisplay
Java Presenter Student Project
JDisplay Download
JDisplay Overwiew
other downloads
troubleshooting JDisplay

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