Invalid escape sequence

Question

I would like to filter out all words containing 1 number and 3 capital letters with a total length of 4. See my example here: http://gskinner.com/RegExr/?32taa

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Answer 1

Your code has two issues:

• Your pattern is wrong, as it allows more digits - see http://regexr.com?32u3e

• Java requires double escape slashes...

Use regex pattern

\\b(?=[A-Z]*\\d[A-Z]*\\b)[A-Z\\d]{4}\\b