Java REGEX - adding possibilities from a list

Question

I need advice for how to create a REGEX in the best way (with as little code as possible). Suppose I have a list (that I don't know it's length before the running time) of Strings, say:

List<String> words = Array.asList("a","b","c");

I want to create this REGEX for example: (a|b|c).* Is a loop necessary for this? Is there a way to do this in one line?

Thanks

There are better ways to do this than a regular expression. Personally I would use words.stream().anyMatch(text::startsWith). — VGR
– VGR, Commented Jan 10, 2020 at 4:59

Andreas · Accepted Answer · 2020-01-09 23:41:16Z

3

Single line:

String regex = words.stream().map(Pattern::quote).collect(Collectors.joining("|", "(", ").*"));

The map(Pattern::quote) part is not necessary if you're absolutely sure that the "words" don't contain any regex-special characters. Keep it, if there is any microscopic chance it could happen.

answered Jan 9, 2020 at 23:41

Andreas

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