Java how to format a string?

Question

I have the following string:

String x = "020120765";

I want this string in the form of 02 0120765. One possibility is:

x = x.substring(0,2) + " " + x.substring(2, x.length());

or:

x = String.format("%s %s", x.substring(0, 2), x.substring(2));

Is there any other better or elegant way? I'm thinking in the direction of regex. I have tried the following:

x = String.format("%s %s", x.split("\\d{2}"));

But it doesn't work.

You can omit x.length() as the second argument to substring, and just write x.substring(2) — Dawood ibn Kareem
– Dawood ibn Kareem, Commented Apr 24, 2014 at 12:05

Alexis C. · Accepted Answer · 2014-04-24 12:02:23Z

8

You could also use a StringBuilder with its insert method:

x = new StringBuilder(x).insert(2, ' ').toString();

answered Apr 24, 2014 at 12:02

Alexis C.

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2 Comments

Pshemo Over a year ago

+1 it seems like the easiest and most straightforward solution.

user3111525 Over a year ago

+1. The position changes, so I only need to insert space if it matches the regex. Otherwise the default string should be the value.

Evgeniy Dorofeev · Accepted Answer · 2014-04-24 12:01:27Z

5

Another option

x = x.replaceAll("(..)(.+)", "$1 $2");

answered Apr 24, 2014 at 12:01

Evgeniy Dorofeev

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1 Comment

user3111525 Over a year ago

Good one. I changed to: x.replaceFirst("(\\d{2})(\\d+)","$1 $2"). How could I not see that. Thanks.

Pshemo · Accepted Answer · 2014-04-24 12:08:03Z

2

If you are interested in regex solution then you can try with

x = x.replaceAll("^..", "$0 ")

^.. will match first first two characters. $0 is reference to match from group 0 (which contains entire match) so $0will replace matched part with itself plus space.

edited Apr 24, 2014 at 12:08

answered Apr 24, 2014 at 12:01

Pshemo

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1 Comment

Dawood ibn Kareem Over a year ago

This seems to me to be the most straightforward way to attack this problem.

DerStrom8 · Accepted Answer · 2014-04-24 13:12:01Z

0

x=String.format("%s %s",x.split("(?<=\\G.{2})", 2))

will not work because you are trying to pass an array in and you have too few arguments. You could, however, do it like this:

x=String.format("%s %s",x.split("(?<=\\G.{2})", 2)[0], x.split("(?<=\\G.{2})", 2)[1]);

Or, more neatly,

String[] arr = x.split("(?<=\\G.{2})", 2);
x = String.format("%s %s", arr[0], arr[1]);

EDIT: I am very inexperienced with regex so please excuse the previous incorrect regex patterns.

edited Apr 24, 2014 at 13:12

answered Apr 24, 2014 at 12:03

DerStrom8

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3 Comments

Pshemo Over a year ago

I am not the downvoter but split("\\d{2}") will remove part matched by \\d{2} which doesn't seem to be what OP wants.

DerStrom8 Over a year ago

I made the mistake of copying the OP's regex. Give me a few minutes and I will fix it

DerStrom8 Over a year ago

Please see the edit. The regex patterns are now correct and have been tested =)

Dawood ibn Kareem · Accepted Answer · 2014-04-24 13:22:03Z

0

x.replaceAll("(?<=^..)", " ");

answered Apr 24, 2014 at 13:22

Dawood ibn Kareem

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