How do you match multiple Regex patterns for a single line of text in Java?

Question

Lets say I have multiple patterns P1, P2, P3,, and so on. These patterns are different Regex patterns to match different variations of DATE.

How do I match these for

Answer 1

To complement the other answers...

You can write one big, hard-to-read pattern using the alternation operator:

r1|r2|r3|...|rn

where r1 etc are themselves "fully-fleged" regexes.

However you have to be careful about the order of alternations: the first to match wins. That is, if the regex engine is not a POSIX regex engine but java.util.regex's engine isn't.

Therefore, with text catflap, using regex:

cat|catflap

Java will match cat; a POSIX regex engine will match catflap (the longest, leftmost match).

Sticking with more individual, maintainable patterns is imho a better option.