Although your question really doesn't make any sense - you haven't given any useful context to it. You could be writing those lines on a page as text, writing a plugin, stuffing things into velocity - there's no sane answer to that question without knowing what you're trying to do and why you think you might need them
I don't know, if I understand your question right, but of course you can import a java.util class.
Here's an example with java.util.x - Classes : http://www.hascode.com/2010/04/how-to-build-a-confluence-macro-plugin/
I did not test it, but maybe it helps you.
maybe you should start reading here:
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