Changing colors and changing a bit of the text of this website is just fun; furthermore this code will easy enable you to auto-comment or auto-like this scenarios (for example; every registered user who opens this scenario will automatically like and post a comment, even if he don't want to). Modifying the code of this website will also enable you to display advertisements, collect user statistics/data or bring in third party code, or viruses etc.. I think its a security issue that i'm using to do this; surely the greenfoot.org team is not willing to publish that code...

One main thing that could realy help you is: ScriptEngineManager manager = new ScriptEngineManager(); ScriptEngine engine = manager.getEngineByName("js"); Object result = engine.eval("3+4");

Cool :) a working calculator :D One bug: double press + - * or / and it will "java.lang.NumberFormatException: empty String" at Background.act(Background.java:82).