I'm interested in learning about the available choices of high-quality, stand-alone source code formatters for Java.

The formatter must be stand-alone, that is, it must support a "batch" mode that is decoupled from any particular development environment. Ideally it should be independent of any particular operating system as well. So, a built-in formatter for the IDE du jour is of little interest here (unless that IDE supports batch mode formatter invocation, perhaps from the command line). A formatter written in closed-source C/C++ that only runs on, say, Windows is not ideal, but is somewhat interesting.

To be clear, a "formatter" (or "beautifier") is not the same as a "style checker." A formatter accepts source code as input, applies styling rules, and produces styled source code that is semantically equivalent to the original source code. A style checker also applies styling rules, but it simply reports rule violations without producing modified source code as output. So the picture looks like this:

Formatter (produces modified source code that conforms to styling rules)

Read Source Code → Apply Styling Rules → Write Styled Source Code

Style Checker (does not produce modified source code)

Read Source Code → Apply Styling Rules → Write Rule Violations

Further Clarifications

Solutions must be highly configurable. I want to be able to specify my own style, not simply select from a canned list.

Also, I'm not looking for a general purpose pretty-printer written in Java that can pretty-print many things. I want to style Java code.

I'm also not necessarily interested in a grand-unified formatter for many languages. I suppose it might be nice for a solution to have support for languages other than Java, but that is not a requirement.

Furthermore, tools that only perform code highlighting are right out.

I'm also not interested in a web service. I want a tool that I can run locally.

Finally, solutions need not be restricted to open source, public domain, shareware, free software, commercial, or anything else. All forms of licensing are acceptable.