pattern matching in java using regular expression

Question

I am looking for a pattern to match this "[email protected]@Po6" and one more "[email protected]@Port-channel7" expression in Java using regular expression.

Like we have \d{1,3}.\d{1,3}.\d{1,3}.\d{1,3} for IP address validation.

Can we have the pattern like below? Please suggest--

[a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9]@\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}@Po\d[1-9]
[a-zA-Z0-9][a-zA-Z0-9][a-zA-Z0-9]@\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}@Port-channel\d[1-9]

Thanks in advance.

==============================

In my program i have,

import java.util.regex.*;
class ptternmatch {
    public static void main(String [] args) {
        Pattern p = Pattern.compile("\\w\\w\\w@\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}@*");
        Matcher m = p.matcher("[email protected]@Port-channel7");
        boolean b = false;
        System.out.println("Pattern is " + m.pattern());
        while(b = m.find()) {
            System.out.println(m.start() + " " + m.group());
    }
    }
}

But i am getting compilation error with the pattern.--> Invalid escape sequence The sequence will be like a ->a 3 character word of digit n letter@ipaddress@some text..

What is the actual question? Which parts of the examples are you having trouble matching? Which parts are variable and which parts are static in your expected data? — Ophidian
– Ophidian, Commented Nov 16, 2010 at 14:15

Ophidian · Accepted Answer · 2010-11-16 14:25:27Z

1

Well, if you want to validate the IP address, then you need something a little bit more involved than \d{1,3}. Also, keep in mind that for Java string literals, you need to escape the \ with \\ so you end up with a single backslash in the actual regex to escape a character such as a period (.).

Assuming the LA5@ bit is static and that you're fine with either Po or Port-channel followed by a digit on the end, then you probably need a regex along these lines:

LA5@(((2((5[0-5])|([0-4][0-9])))|(1[0-9]{2})|([1-9][0-9]?)\\.){3}(2(5[0-5]|[0-4][0-9]))|(1[0-9]{2})|([1-9][0-9]?)@Po(rt-channel)?[1-9]

(Bracketing may be wonky, my apologies)

answered Nov 16, 2010 at 14:25

Ophidian

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icyrock.com · Accepted Answer · 2010-11-16 14:15:56Z

0

You can do something like matcher.find() and, if it is true, the groups to capture the information. Take a look a the tutorial here:

http://download.oracle.com/javase/tutorial/essential/regex/

You would need to wrap the necessary parts int parentheses - e.g. (\d{1,3}). If you wrap all 4, you will have 4 groups to access.

Also, take a look at this tutorial

http://www.javaworld.com/javaworld/jw-07-2001/jw-0713-regex.html?page=3

It's a very good tutorial, I think this one would explain most of your questions.

To match the second of your strings:

[email protected]@Port-channel7

you can use something like:

\w{2}\d@\d{1,3}.\d{1,3}.\d{1,3}.\d{1,3}@[a-zA-Z\-]+\d

This depends on what you want to do, so the regex might change.

edited Nov 16, 2010 at 14:15

answered Nov 16, 2010 at 13:59

icyrock.com

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2 Comments

Andreas Dolk Over a year ago

I think, he is looking for the exact Java regExp pattern to find those example strings.

icyrock.com Over a year ago

@Andreas_D I misunderstood it the first time... Thank you!

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