Regular Expressions in Using Pattern java

Question

I have a string as below.

$Alarm:com.Alarm(a  ==  123 || (count  ==  12345 , time  matches  "24"))

whenever i encounter the above string i need to generate the following string.I mean i need to append the string "from Stream" as below.

$Alarm:com.Alarm(a  ==  123 || (count  ==  12345 , time  matches  "24")) from Stream.

I am currently using the following pattern to acheive the same in java.

Pattern eventPattern = Pattern.compile(".*?\\.Alarm\\(.*?\\)");

But i am getting the following output.

$Alarm:com.Alarm(a  ==  123 || (count  ==  12345 , time  matches  "24") from Stream )

Please provide me some pointers to acheive the correct output.The regular expression should consider only the last paranthesis.

Can you show some code on how you are using your eventPattern? — beny23
– beny23, Commented Apr 11, 2012 at 11:25

John B · Accepted Answer · 2012-04-11 11:44:18Z

1

You need to include parens matching in your Pattern. Something like the following:

Pattern eventPattern = Pattern.compile(".*?\\.Alarm\\(([^\\(]*?|\\([^\\)]*?\\))*\\)");

Things up to and including the first open parens: .*?\\.Alarm\\(

Stuff outside any internal parens: [^\\(]*?

Internal parens pair: \\([^\\)]*?\\)

Match any number of stuff outside parens or within a parens pair: ([^\\(]*?|\\([^\\)]*?\\))*

This RegexPlanet site is a great place to play with regexes to see what will work.

answered Apr 11, 2012 at 11:35

John B

33.1k8 gold badges80 silver badges100 bronze badges

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

3 Comments

Which will effectively only work if the maximum level of nesting of brackets is known in advance. Regular expressions aren't Turing-complete...

Good point - poster needs to answer to what degree this is an issue

My requirment is irrespective of the number of parantesis[")"].The string needs to append to only after last closing paranthesis[")"].