CODEWITHSUNDEEP
javaregex
jonathan1987
jonathan1987

Reputation: 261

Java Regex Finding digits in a String

I am trying to find digits in a string. I know that in finding a digit is done by \d but when I try it on a sample text like the following:

127.0.0.1 - - [11/Dec/2012:11:57:36 -0500] "GET http:// localhost/ HTTP/1.1" 503 418 "-" "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.95 Safari/537.11"

using my java code

Pattern test = Pattern.compile("\\d");
testLine = in.readLine(); // basically the text above 
// extract date and time log in and number of times a user has hit the page
numTimesAccess++; // increment number of lines in a count   
System.out.println(test.matcher(testLine).group());
System.out.println(test.matcher(testLine).start());
System.out.println(test.matcher(testLine).end());

I get an error exception stating that No Match is found. Is something wrong with my regular expression patter or in the way I am trying to access the text matching the patterns.

Upvotes: 2

Views: 11687

Answers (4)

Serg Burlaka
Serg Burlaka

Reputation: 2496

just add and use the simple ktx:

 fun String.digits() = 
      Pattern.compile("\\d+").matcher(this).run { if (find()) group() else "" }!!

Upvotes: 0

Sreyan
Sreyan

Reputation: 367

Try using \d* instead of \d+. Have a look at this post-: Finding a Number in a string.

Upvotes: 0

PermGenError
PermGenError

Reputation: 46408

Firstly, you should call Matcher.find() before you invoke Matcher.group()

use "\\d+" as regex if you consider 127 as a whole single digit.

        Pattern p = Pattern.compile("\\d+");
        Matcher m = p.matcher(s);
        while(m.find()){
        System.out.println(m.group() + " " + m.start() + " " + m.end());
        }

Upvotes: 7

jlordo
jlordo

Reputation: 37813

If you really want to find single digits, you need this:

Pattern pattern = Pattern.compile("\\d");
Matcher matcher = pattern.matcher(testline);
while (matcher.find()) {
    System.out.println(matcher.group());
}

if you want to find non-floating-point numbers, change the regex to "\\d+".

Upvotes: 0

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