CODEWITHSUNDEEP
javaregex
user2166045
user2166045

Reputation: 73

Remove leading trailing non numeric characters from a string in Java

I need to strip off all the leading and trailing characters from a string upto the first and last digit respectively.

Example : OBC9187A-1%A
Should return : 9187A-1

How do I achieve this in Java?

I understand regex is the solution, but I am not good at it.
I tried this replaceAll("([^0-9.*0-9])","")
But it returns only digits and strips all the alpha/special characters.

Upvotes: 4

Views: 3148

Answers (2)

MaxZoom
MaxZoom

Reputation: 7753

This will strip leading and trailing non-digit characters from string s.

String s = "OBC9187A-1%A";
s = s.replaceAll("^\\D+", "").replaceAll("\\D+$", "");
System.out.println(s);
// prints 9187A-1

DEMO

Regex explanation
^\D+

^ assert position at start of the string
\D+ match any character that's not a digit [^0-9]
     Quantifier: + Between one and unlimited times, as many times as possible

\D+$

\D+ match any character that's not a digit [^0-9]
     Quantifier: + Between one and unlimited times, as many times as possible
  $ assert position at end of the string

Upvotes: 3

brso05
brso05

Reputation: 13222

Here is a self-contained example of using regex and java to solve your problem. I would suggest looking at a regex tutorial of some kind here is a nice one.

public static void main(String[] args) throws FileNotFoundException {
    String test = "OBC9187A-1%A";
    Pattern p = Pattern.compile("\\d.*\\d");
    Matcher m = p.matcher(test);

    while (m.find()) {
        System.out.println("Match: " + m.group());
    }
}

Output:

Match: 9187A-1

\d matches any digit .* matches anything 0 or more times \d matches any digit. The reason we use \\d is to escape the \ for Java since \ is a special character...So this regex will match a digit followed by anything followed by another digit. This is greedy so it will take the longest/largest/greediest match so it will get the first and last digit and anything in between. The while loop is there because if there was more than 1 match it would loop through all matches. In this case there can only be 1 match so you can leave the while loop or change to if like this:

if(m.find()) 
{
    System.out.println("Match: " + m.group());
}

Upvotes: 3

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