Might sound strange but: Yes it is. Since the first JDBC DB drivers it's common sense to use prepared statements and not build a query on your own. Because of this SQL injection is a much much smaller problem in Java codebases than in PHP ones.
(this being a Java culture result more than a language one).
I meant than PHP. The implication seemed to be "WordPress is made with PHP, and WordPress isn't bank-quality software, so would you want to trust your money to something made with PHP?" I would trust the credentials of the people behind the site before I'd even give a second's thought to the programming language. (Of course, that doesn't help Mt Gox much either.)
The Java language is designed for safety, above performance, and ease of creating code. So it is more expensive to create a Java financial system. But safer.
The quality of your programmer makes more difference than your choice of language and libraries. But your choice of language and libraries has SOME effect. And Java tends to be safer than PHP.