Oh, you mean a code block? Like on any other mediawiki site.
<nowiki>Start with a space in the first column,
(before the <nowiki>).
Then your block format will be
maintained.
This is good for copying in code blocks:
def function():
"""documentation string"""
if True:
print True
else:
print False</nowiki>
I might add a dedicated color-syntax code block here soon, need to find a good one to add.
EDIT1: I added GeSHi and defaulted it to java, so you can just surround code in <source></source> or <syntaxhighlight></syntaxhighlight> blocks on the wiki now. The options you can see here.
EDIT2: I went ahead and updated your page, I added the lang="java" bits even though it is not necessary just because your top code element was already like that, but they are unneeded, just use <source></source> will default to java, as what makes sense on this wiki.
The animation that fills the banner in combination with the size of it is... distracting, plus it is not giving any useful information.