How to extract a string after and before a specific word using Java regular expression

Question

I need to extract a string after opResult and before another string (word+ '=')

For example:

testest=false opResult=Critical extension not supported random=abc srcPort=10

So I should extract out Critical extension not supported, before the next word with an equals sign.

Also, it should also work if there is no other string at the back, meaning I should get the same result with the below example.

typesOnly=false opResult=Critical extension not supported

The regular expression I have currently extracted everything before the last '=' sign.

opResult=(\S.*)(\s\w+=)

Tim Biegeleisen · Accepted Answer · 2017-07-10 06:27:39Z

2

We can try matching/extracting using the following pattern:

.*opResult=(.*?)(?:\\s*\\S+=.*|$)

The trick here is in being able to articulate when the next key begins, and then to not extract it.

String line = "testest=false opResult=Critical extension not supported random=abc srcPort=10";
String pattern = ".*opResult=(.*?)(?:\\s*\\S+=.*|$)";
Pattern r = Pattern.compile(pattern);
Matcher m = r.matcher(line);
if (m.find( )) {
    System.out.println(m.group(1));
}

Output:

Critical extension not supported

Demo here:

Rextester

edited Jul 10, 2017 at 6:27

answered Jul 10, 2017 at 6:21

Tim Biegeleisen

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3 Comments

Salt Over a year ago

It only works if there are string at the back but it should also work if there is no string at the back.

Tim Biegeleisen Over a year ago

I just updated to cover the case where opResult is the final key in the string. Other than this, I don't know what you mean.

Salt Over a year ago

Yes, that's what I wanted! Thank you!!

Chiranjib · Accepted Answer · 2017-07-10 07:04:21Z

0

We need to find text after 'opResult=' before the next blankspace(\s)word(\w+) followed by an equals sign (?==) and whatever follows (.*)

Pattern becomes

.*opResult=([\w|\s]+)(\s\w+(?==).*)

Here's the link to Regex101

answered Jul 10, 2017 at 7:04

Chiranjib

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Comments

Flown · Accepted Answer · 2017-07-10 09:14:08Z

0

You should work with positive lookbehind and positive lookahead and a lazy quantifier for the text in between

(?<=opResult=).*?(?=\s*\S*=)

You can see the results on regex101.

edited Jul 10, 2017 at 9:14

answered Jul 10, 2017 at 6:17

Flown

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2 Comments

Salt Over a year ago

it shouldn't grab the random word, should only get 'Critical extension not supported'

Flown Over a year ago

@Kaycee Didn't see it, but here you go.

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