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How to extract first 3 characters from an alphanumeric string in Java? For example- if the alphanumeric string is 12A12D3F34DFdHNB38HG. So I want to extract ADF

Garima Virmani
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    What about the code you use? Also, non accentuated Latin letters are not the only alphabetic characters... – fge Aug 03 '16 at 17:07
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    [String.substring()](https://docs.oracle.com/javase/7/docs/api/java/lang/String.html#substring(int,%20int)) – jonhopkins Aug 03 '16 at 17:08
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    Post your code. This regex should work fine. – Pshemo Aug 03 '16 at 17:15
  • Seeing as `String`s consist entirely of `char`acters, it's not clear what you mean by "*it only works if the string is starting with a character*". Please include what you've tried so far and a clear description of the problem you're running into. "It doesn't work" isn't something we can diagnose. – dimo414 Aug 03 '16 at 18:23
  • You may use Pattern.compile("[a-zA-Z]{3}") – JavaHopper Aug 03 '16 at 18:28
  • Possible duplicate of [up to first N characters](http://stackoverflow.com/questions/1583940/up-to-first-n-characters) – Inzimam Tariq IT Aug 03 '16 at 18:59
  • It can be done with an easy [`s.replaceAll("(?i)^[^a-z]*([a-z])[^a-z]*([a-z])[^a-z]*([a-z]).*$", "$1$2$3")`](https://regex101.com/r/uD5cO0/1). – Wiktor Stribiżew Aug 03 '16 at 20:15
  • Wiktor Stribizew- Thank you, its working – Garima Virmani Aug 05 '16 at 04:10

2 Answers2

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To extract the first three characters of a String, you can simply use the substring() method in the String class.

String firstThreeCharacters = str.substring(0, 3);

If this was not what you are asking for, please clarify your question since it is arguably ambiguous.

EDIT: @Wiktor Stribiżew has a good answer for your clarified question. I'm re-posting it here to make the answer more visible for other users.

String firstThreeCharacters = str.replaceAll("(?i)^[^a-z]*([a-z])[^a-z]*([a-z])[^a-z]*([a-z]).*$", "$1$2$3")
Micah Stairs
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  • actually i have a alphanumeric string. For eg-A12D3F376HF7H23H87JH. So I want to extract first three alphabets so i want the output to be ADF – Garima Virmani Aug 05 '16 at 04:04
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You need pattern as : [a-zA-z0-9]{3}

Shekhar Khairnar
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