Any character including newline - Java Regex

I thought it may be [.\n]+ but that doesn't seem to work?

The dot cannot be used inside character classes.

See the option Pattern.DOTALL.

Pattern.DOTALL Enables dotall mode. In dotall mode, the expression . matches any character, including a line terminator. By default this expression does not match line terminators. Dotall mode can also be enabled via the embedded flag expression (?s). (The s is a mnemonic for "single-line" mode, which is what this is called in Perl.)

If you need it on just a portion of the regular expression, you use e.g. [\s\S].

Edit: While my original answer is technically correct, as ThorSummoner pointed out, it can be done more efficiently like so

[\s\S]

as compared to (.|\n) or (.|\n|\r)