Get Sub-string from String with specific Pattern in JAVA

Question

I have the following input:

8=FIX.4.2|9=00394|35=8|49=FIRST|8=FIX.4.2|9=00394|35=8|56=MIDDLE|10=245|8=FIX.4.2|9=00394|35=8|49=LAST|56=HEMADTS|10=024|

Now I want the strings that are starting with "8=???" and end with "10=???|". You can see above that there are exactly two strings that start with 8 and end with 10. I have written a program for this.

Below is my code:

public class Main {
  static Pattern r = Pattern.compile("(.*?)(8=\\w\\w\\w)[\\s\\S]*?(10=\\w\\w\\w)");

  public static void main(String[] args) {     
       String str = "8=FIX.4.2|9=00394|35=8|49=FIRST|8=FIX.4.2|9=00394|35=8|56=MIDDLE|10=245|8=FIX.4.2|9=00394|35=8|49=LAST|56=HEMADTS|10=024|";
       match(str);
  }

  public static void match(String message) { //send to OMS

        Matcher m = r.matcher(message);
        while (m.find()) {
              System.out.println(m.group());
        }
   }
}

When I just run this I am getting the wrong output like:

8=FIX.4.2|9=00394|35=849=FIRST`|8=FIX.4.2|9=00394|35=8|56=MIDDLE|10=245|`
8=FIX.4.2|9=00394|35=849=LAST|56=HEMADTS|10=024|

You can see the first string in the output. It consists of "8=???" two times but the exact output needs to be like:

8=FIX.4.2|9=00394|35=8|56=MIDDLE|10=245|
8=FIX.4.2|9=00394|35=849=LAST|56=HEMADTS|10=024|

I also want the un-matched strings in separate as there is a further work with those strings. How can I get that? So, the total output needs to be like:

Matched : 8=FIX.4.2|9=00394|35=8|56=MIDDLE|10=245|
Matched : 8=FIX.4.2|9=00394|35=849=LAST|56=HEMADTS|10=024|
UnMatched : 8=FIX.4.2|9=00394|35=849=FIRST`|

I don't understand why the two currently matching strings don't meet your expectation. — Tim Biegeleisen
– Tim Biegeleisen, Commented Aug 18, 2017 at 13:21
Take the two currently matching strings. The first string has TWO "8=???" but the exact match is only ONE "8=???" to "10=???" — hema chandra
– hema chandra, Commented Aug 18, 2017 at 13:24
I see at least 4 strings that start with 8= and end with 10= in your input example. — Nick
– Nick, Commented Aug 18, 2017 at 13:26
Sorry, there are only two strings that exactly start with "8=FIX.4.2" and end with "10=XXX". — hema chandra
– hema chandra, Commented Aug 18, 2017 at 13:29
8=FIX.4.2 appears 3 times, 10= appears twice. Do you mean a match that does not include another 8=FIX.4.2? — Nick
– Nick, Commented Aug 18, 2017 at 13:31

Wiktor Stribiżew · Accepted Answer · 2017-08-18 13:45:13Z

3

You need to use a tempered greedy token to match the shortest window possible between 2 strings. That will solve the first problem. To get unmatched strings, just split the string with the pattern.

Use

\b8=\w{3}(?:(?!8=\w{3})[\s\S])*?10=\w{3}\|

See the regex demo.

Details

\b - a word boundary
8= - a literal substring
\w{3} - 3 word chars
(?:(?!8=\w{3})[\s\S])*? - a tempered greedy token matching any char ([\s\S]), zero or more times, as few as possible, that do not start a 8= and 3 word chars pattern
10= - a literal substring
\w{3} - 3 word chars
\| - a literal |.

Java code:

public static Pattern r = Pattern.compile("\\b8=\\w{3}(?:(?!8=\\w{3})[\\s\\S])*?10=\\w{3}\\|");
public static void main (String[] args) throws java.lang.Exception
{
   String str = "8=FIX.4.2|9=00394|35=8|49=FIRST|8=FIX.4.2|9=00394|35=8|56=MIDDLE|10=245|8=FIX.4.2|9=00394|35=8|49=LAST|56=HEMADTS|10=024|";
   match(str);
}
public static void match(String message) { //send to OMS
    Matcher m = r.matcher(message);
    System.out.println("MATCHED:");
    while (m.find()) {
       System.out.println(m.group());
    }
    System.out.println("UNMATCHED:");
    String[] unm = r.split(message);
    for (String s: unm) {
        System.out.println(s);  
    }
}

See the Java demo.

Results:

MATCHED:
8=FIX.4.2|9=00394|35=8|56=MIDDLE|10=245|
8=FIX.4.2|9=00394|35=8|49=LAST|56=HEMADTS|10=024|
UNMATCHED:
8=FIX.4.2|9=00394|35=8|49=FIRST|

edited Aug 18, 2017 at 13:45

answered Aug 18, 2017 at 13:42

Wiktor Stribiżew

631k41 gold badges502 silver badges632 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Tim Biegeleisen Over a year ago

I think I misunderstood the input string and/or spent no time actually testing in Java. +1 in any case.

Collectives™ on Stack Overflow

Get Sub-string from String with specific Pattern in JAVA

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related