SwingJSDemo

Code for Bioinformatics short workshop, University of Dundee, 31st May 2019

Goals

• To give a flavour of cross-compilation of Java Swing to Javascript in action

Pre-requisites

• Eclipse for Java, version 4.8 or later
• git installed (or Eclipse git plugin)
• Java 8 or later

Instructions

To run as Java:

1. Clone this repository (https://github.com/gmungoc/SwingJSDemo.git)
2. Import into Eclipse (Import from Git) as a Java project
3. Run class HelloWorld.java as a Java application and explore its (very simple) functionality

To translate ('transpile') from Swing to Javascript:

1. Right-click on build-site.xml and 'Run as Ant Build' - this unzips swingjs/SwingJS-site.zip to /site
2. Refresh the workspace - you should now see a new folder site
3. Copy file swingjs\net.sf.j2s.core.jar to the dropins subfolder of your Eclipse installation
4. Restart Eclipse to pick up the 'Compiler Participant' plugin
   • if this doesn't work first time, you may need to restart Eclipse with the -clean flag (once only)
5. Select Project | Clean... to recompile the code
   • notice file .j2s - this is needed to enable JavaToScript 'transpilation'
6. Refresh project: you should now see a file site/swing_demo_HelloWorld.html
   • the transpiler generates an html launch page for each Java class with a main method
7. Open this file in a browser (e.g. browse to file, double-click, or right-click and Open With | System Editor)
   • ABC - Anything But Chrome (as Chrome by default doesn't allow local file access)
8. You should now see the code running as Javascript
9. Try making a change to the Java code; it should recompile (as Java) and transpile (to HelloWorld.js)
10. Reload the web page to see the changes
11. Add a main method to HelloWorld2, consisting of new HelloWorld2().display(), and run it
    • tip: type ma then Ctrl-space for the main method template
    • experiment with dragging the mouse, with or without the Shift key pressed
12. A second .html file should have been generated, for HelloWorld2. Try this in the browser. This demonstrates drawing on a SwingJS Graphics context.
13. Transpilation is not just for GUI applications!
    • run PrimeNumberFinder (as Java)
    • run PrimeNumberFinder (as html/Javascript)
    • to fix the error (pass in an argument): add args: "100", to the Info block of the html

SwingJS is currently maintained at https://github.com/BobHanson/java2script, a fork of https://github.com/java2script/java2script.