Java regex pattern to find 3 letters palindrome in a input string

Question

Im trying to find regex pattern in java to find if a string includes a 3 letter palindrome like :

score 2 · Accepted Answer · answered Sep 15 '18 at 13:28

2

For a three letter palindrome you may use the following pattern:

^(?=.*([a-zA-Z])[a-zA-Z]\1)[a-zA-Z .]+$

^ Assert position beginning of string.
(?=.*([a-zA-Z])[a-zA-Z]\1) Positive lookahead. Ensure that at some point in the string there is a letter (([a-zA-Z])), which is followed by a different letter ([a-zA-Z]) and then the same letter again (\1).
[a-zA-Z .]+ Character set for letters, whitespace and ., one or more +.
$ Assert position end of string.

Regex demo here.

For test strings:

answered Sep 15 '18 at 13:28

Paolo

This is what exactly I need.. Thank you..You made my day – learningBird Sep 15 '18 at 13:37
Great to hear, you are welcome. – Paolo Sep 15 '18 at 13:37
it is not working yet. i just click the link you provided, however it only machets `e` of `eye` , `n` of `nan`. what is wrong? – The Scientific Method Sep 15 '18 at 13:37
@TheScientificMethod You are mistaken. The `e` is in the capturing group but the entire string is matched. – Paolo Sep 15 '18 at 13:38
i got it. so the requirement is to match the line with palindrom, not the palidrom word itself. i thought to match the palindrom word. – The Scientific Method Sep 15 '18 at 13:40
1

Correct, the first line in the question states that: *to find if a string includes a 3 letter palindrome* – Paolo Sep 15 '18 at 13:40

1 Answers1