Using regex with replaceAll

Question

I have this regex which is used to validate phone numbers.

^\\(?(\\d{2,3})\\)?[-(). ]?(\\d{2,3})[-(). ]?(\\d{4})$

(Yes, I know it is not perfect, but I don't really care). I am just using it to replace phone numbers with another string, say ### to remove sensitive information. So false positives are fine.

It works when the string I am searching is only a phone number. This works:

String PHONE_PATTERN = "^\\(?(\\d{2,3})\\)?[-(). ]?(\\d{2,3})[-(). ]?(\\d{4})$";
String phone = "123-123-1234";
System.out.println(s.replaceAll(PHONE_PATTERN, "###")); //prints '###'

But with surrounding text it does not work:

String PHONE_PATTERN = "^\\(?(\\d{2,3})\\)?[-(). ]?(\\d{2,3})[-(). ]?(\\d{4})$";
String phone = "some other text 123-123-1234";
System.out.println(s.replaceAll(PHONE_PATTERN, "###"));

By does not work, I mean the text is printed unchanged.

What do I need to change on my regex to get this to work so that the second example prints

some other text ###

How did you end up with ^ and & automatically when building your regex? When I write a regex, I have to actively think about whether either of them should be there, like "Do I only need to match this at the beginning of strings/lines?" — ADTC
– ADTC, Commented Jun 19, 2014 at 20:01
@ADTC I'm a complete noob when it comes to regex. I was just working off what I had found at this site: zparacha.com/… — jlars62
– jlars62, Commented Jun 19, 2014 at 23:48

Chronio · Accepted Answer · 2014-06-19 19:09:26Z

6

Remove the ^ and $ from the beginning and end of your expression. Those characters match the beginning and end of a String, but you don't want the phone number to be the only content of the String, so you should remove them.

answered Jun 19, 2014 at 19:09

Chronio

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anubhava · Accepted Answer · 2014-06-19 19:09:52Z

5

Instead of anchors ^ and $ use \b (word boundary):

String PHONE_PATTERN = "\\b\\(?(\\d{2,3})\\)?[-(). ]?(\\d{2,3})[-(). ]?(\\d{4})\\b";

answered Jun 19, 2014 at 19:09

anubhava

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Amal · Accepted Answer · 2014-06-19 22:15:36Z

4

You need to remove the beginning of string ^ and end of string $ anchors, with having both of these set you're matching the entire string from the first character in the string until the last character in the string.

The ^ stipulates the pattern must match the substring starting with the first character in the string.
The $ stipulates the pattern must match the substring ending with the last character in the string.

If you want to search for a pattern that is at one end or the other, that is when you need to use anchors.

edited Jun 19, 2014 at 22:15

Amal

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answered Jun 19, 2014 at 19:09

hwnd

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