How to find string pattern written between 2 ### in a paragraph

[rajesh76]

Hi,
The project i'm working on is like this..
i have a String variable which stores something like a paragraph. from this i need to find all the occurances of the substring ###_______###. the value between ### can be anything..

i was thinking of using the split() function and comparing if each string stored has 2 ### patterns. but this seems a very inefficient way of coding, especially since the number of words can be huge.

can u please suggest any approach or function that i could use.. i don't know much abt regex, i have tried searching, but haven't really found anything useful yet..

thanks in advance..

[Muskar]

I'm not sure what you want but finding the following three substrings is quite easy:

import java.util.ArrayList;

public class Paragraph {
    public static void main(String[] args) {
        ArrayList<String> strings = new ArrayList<String>();
        String s1 = "###substring###";
        String s2 = "###example###";
        String s3 = "###whatever###";
        strings.add(s1);
        strings.add(s2);
        strings.add(s3);
        
        for (String s : strings) {
            int indexOfFirstChar = s.indexOf("###")+3;
            int indexOfLastChar = s.indexOf("###", indexOfFirstChar)-1;
            System.out.println(s.substring(indexOfFirstChar, indexOfLastChar+1));
        }
    }
}

which returns the output:

substring
example
whatever

[DarrylBurke]

i don't know much abt regex

Start learning here:
Regular-Expressions.info - Regex Tutorial, Examples and Reference - Regexp Patterns
Lesson: Regular Expressions (The Java™ Tutorials > Essential Classes)
and of course the Pattern API.

What you want is a regex that reluctantly matches anything, with positive look-behind and look-ahead that match '###', and to use that with Matcher#find() in a loop.

db

[rajesh76]

thank you for the suggestion and the link, the index method might help. Actually the paragraph i mentioned is an xml converted to a string. i'll have something like <Name>###Black###</Name>. Once i find the pattern i need to check if the opening and closing tags are the same.. any suggestion on how i could try that would be a great help..