Check if word contains substring in Java Regex

Question

If I want to check all words that contain the substring DEF, would this be the right approach:

^.*[D][E][F].*$

Also is there an easy rule when negating regexes, i.e. modifying the above to identify strings that don't contain DEF

EDIT: I know this doesn't require regexes, but for my purposes it does.

Answer 1

This works too:

^.*DEF.*$

It checks, if the whole String contains the substring "DEF" at least once. But for trivial expressions like this:

str.contains("DEF");

does the same.