java - how to add - every after 3rd digit of String number

Question

i have contact number which i am getting from parameter which is of type String.

 String pharmacyPhone = "123456789";

here i want to add - after every 3rd digit and before 4th digit

so the output will become like pharmacyPhone = 123-456-789.

so how to achieve this?

Please include some code to show us, what you have already achieved. — npkllr, Sep 21 '18 at 08:16
Take a look to [StringBuilder](https://docs.oracle.com/javase/7/docs/api/java/lang/StringBuilder.html).insert(offset, char) — Alessandro, Sep 21 '18 at 08:18

score 3 · Accepted Answer · answered Sep 21 '18 at 08:18

3

One approach uses a regex replacement:

String pharmacyPhone = "123456789";
pharmacyPhone = pharmacyPhone.replaceAll("(.{3})(?=.)", "$1-");
System.out.print(pharmacyPhone);

123-456-789

The pattern (.{3})(?=.) works by matching and capturing three digits at a time, provided that there is at least one more digit which follows. It then replaces with those captured three digits followed by a dash. The positive lookahead (?=.) ensures that we don't add a dash at the end of the string.

answered Sep 21 '18 at 08:18

Tim Biegeleisen

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Nice one. Tim got any reference for regex tut? – pratikpawar Sep 21 '18 at 08:21
www.rexegg.com is a very good one. Other than that, practice is how one generally gets good at anything; regex is no exception to this. – Tim Biegeleisen Sep 21 '18 at 08:22
Indeed ack. Thanks for ref. – pratikpawar Sep 21 '18 at 08:23
thanks a lot, it working as i aspected – Lalit Dubey Sep 21 '18 at 08:59
sure..thanks @TimBiegeleisen – Lalit Dubey Sep 27 '18 at 15:24
what to add if we want like 123-456-7890 for the input 1234567890? – Lalit Dubey Oct 04 '19 at 16:00
[Check the demo](https://rextester.com/HCYS38924) – Tim Biegeleisen Oct 05 '19 at 00:38

java - how to add - every after 3rd digit of String number

1 Answers1