Java RegEX and group

Question

I need to parse log files and get some values to variable. The log file will have a string

String logStr = "21:19:03 -[ 8b4]- ERROR - Jhy AlarmOccure::OnAdd - Updated existing alarm: ID [StrValue1:StrValu2|StrValue3], Instance [4053], SetStatus [0], AckStatus [1], SetTime [DateValue4], ClearedTime [DateValue5]";

I need to get StrValue1,StrValue2,StrValue3,DateValue4 and DateValue5 to varaibles these values are changing fields when ever there is an error.

First i was trying to at least get StrValue1. But not getting the expected result.

Pattern twsPattern = Pattern.compile(".*?ID ?[([^]:]*):([^]|]*)|([^]]*)]");//.*ID\\s$.([^]:]*.):.([^]|]*.)|.([^]]*.).]
Matcher twsMatcher = twsPattern.matcher(logStr);
if(twsMatcher.find()){
    System.out.println(twsMatcher.start());
    System.out.println(twsMatcher.group());
    System.out.println(twsMatcher.end());
}

I am not able to understand the grouping stuff, in regex.

Adam Siemion · Accepted Answer · 2013-07-18 23:31:19Z

2

Try regexp ([a-zA-z]+) \[([^\]]+)\].

For string 21:19:03 -[ 8b4]- ERROR - Jhy AlarmOccure::OnAdd - Updated existing alarm: ID [StrValue1:StrValu2|StrValue3], Instance [4053], SetStatus [0], AckStatus [1], SetTime [DateValue4], ClearedTime [DateValue5] it returns:

ID and StrValue1:StrValu2|StrValue3
Instance and 4053
SetStatus and 0
AckStatus and 1
SetTime and DateValue4
ClearedTime and DateValue5

You can test it here.

answered Jul 18, 2013 at 23:31

Adam Siemion

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1 Comment

paramupk Over a year ago

Thanks for the answer... Since the strings are coming from log files by an application these will be constant..

Andrew Cheong · Accepted Answer · 2013-07-18 23:31:36Z

2

Good on you for the attempt! You're actually doing quite well. You need to escape square brackets that you don't mean as character classes, i.e.

.*?ID ?\[
       ^

And hopefully you are aware that by ([^]:]*) you are meaning, "The longest possible string of characters without a closing square bracket or colon."

You probably also want to escape the |, as that is an alternation operator in regular expressions, i.e.

\|

answered Jul 18, 2013 at 23:31

Andrew Cheong

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acdcjunior · Accepted Answer · 2013-07-18 23:41:31Z

Long story short, your regex lacks escaping some chars, like [ and | (this one, if outside a character class - []).

So when you want to actually match the [ char, you have to use \[ (or \\[ inside the java string). Also, the negation in the group ([^]:]*) is not what it seems. You probably want just ([^:]*), which matches everything until a :.

To make it work, then, you would simply use Matcher#group(int) to retrieve the values. This is the adapted code with the final regex:

String logStr = "21:19:03 -[ 8b4]- ERROR - Jhy AlarmOccure::OnAdd - Updated existing alarm: ID [StrValue1:StrValu2|StrValue3], Instance [4053], SetStatus [0], AckStatus [1], SetTime [DateValue4], ClearedTime [DateValue5]";
Pattern twsPattern = Pattern.compile(".*?ID ?\\[([^:]*):([^|]*)\\|([^\\]]*)\\].*?SetTime ?\\[([^\\]]*)\\][^\\[]+\\[([^\\]]*)\\]");
Matcher twsMatcher = twsPattern.matcher(logStr);
if (twsMatcher.find()){
    System.out.println(twsMatcher.group(1)); // StrValue1
    System.out.println(twsMatcher.group(2)); // StrValu2
    System.out.println(twsMatcher.group(3)); // StrValue3
    System.out.println(twsMatcher.group(4)); // DateValue4
    System.out.println(twsMatcher.group(5)); // DateValue5
}

acdcjunior · Accepted Answer · 2013-07-22 03:21:11Z

I like more general solutions, but here is a very specific pattern you can use if it suits you. It will capture all of the values in a string as long as they are follow the same, very specific pattern.

ID (?:\[([^\]:]+):([^\]|]+)\|([^\]]+)\]).*?SetTime \[([^\]]+)\], ClearedTime \[([^\]]+)\]

Here is the result:

1: ID [StrValue1:StrValu2|StrValue3], Instance [4053], SetStatus [0], AckStatus [1], SetTime [DateValue4], ClearedTime [DateValue5]
  [1]: StrValue1
  [2]: StrValu2
  [3]: StrValue3
  [4]: DateValue4
  [5]: DateValue5

Try it out

Multiple Matches per line

This version will just match each instance in a string of ID, SetTime, or ClearedTime followed by a bracketed value.

(ID|SetTime|ClearedTime) \[([^\]]+)\

Results

1: ID [StrValue1:StrValu2|StrValue3]
  [1]: ID
  [2]: StrValue1:StrValu2|StrValue3
1: SetTime [DateValue4]
  [1]: SetTime
  [2]: DateValue4
1: ClearedTime [DateValue5]
  [1]: ClearedTime
  [2]: DateValue5

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