Regular Expressions 101

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An explanation of your regex will be automatically generated as you type.
Detailed match information will be displayed here automatically.
  • All Tokens
  • Common Tokens
  • General Tokens
  • Anchors
  • Meta Sequences
  • Quantifiers
  • Group Constructs
  • Character Classes
  • Flags/Modifiers
  • Substitution
  • A single character of: a, b or c
    [abc]
  • A character except: a, b or c
    [^abc]
  • A character in the range: a-z
    [a-z]
  • A character not in the range: a-z
    [^a-z]
  • A character in the range: a-z or A-Z
    [a-zA-Z]
  • Any single character
    .
  • Alternate - match either a or b
    a|b
  • Any whitespace character
    \s
  • Any non-whitespace character
    \S
  • Any digit
    \d
  • Any non-digit
    \D
  • Any word character
    \w
  • Any non-word character
    \W
  • Match everything enclosed
    (?:...)
  • Capture everything enclosed
    (...)
  • Zero or one of a
    a?
  • Zero or more of a
    a*
  • One or more of a
    a+
  • Exactly 3 of a
    a{3}
  • 3 or more of a
    a{3,}
  • Between 3 and 6 of a
    a{3,6}
  • Start of string
    ^
  • End of string
    $
  • A word boundary
    \b
  • Non-word boundary
    \B

Regular Expression
No Match

`
`

Test String

Code Generator

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "^.+>[\\d]\\s(?P<Date>\\d{4}-\\d{2}-\\d{2})T(?P<Time>\\d{2}:\\d{2}:\\d{2}).+firewall,info\\s(?P<RadUser>\\d+).+in:(?P<InputInterface>[^,]+)\\s+out:(?P<OutputInterface>[^,]+),\\s+(?:src-mac\\s+(?P<SourceMacAddress>[^,]+),\\s+)?proto\\s+(?P<Protocol>\\w+)(?:\\s+\\((?P<Flags>[^)]+)\\))?,\\s+\\[?(?P<SrcIP>\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}|[a-f\\d:]+)\\]?(?::(?P<SrcPort>\\d+))?->\\[?(?P<DstIP>\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}\\.\\d{1,3}|[a-f\\d:]+)\\]?(?::(?P<DstPort>\\d+))?,\\s(?P<NAT>\\w+)\\s\\((?P<SrcIpLocalNat>\\b(?:\\d{1,3}\\.){3}\\d{1,3}\\b):(?P<SrcPortLocalNat>\\d+)->(?P<SrcIpPublicNat>\\b(?:\\d{1,3}\\.){3}\\d{1,3}\\b):(?P<SrcPortPublicNat>\\d+)\\)->(?P<DestIpNat>\\b(?:\\d{1,3}\\.){3}\\d{1,3}\\b):(?P<DestPortNat>\\d+),.+"; final String string = "<13>1 2022-05-17T09:10:28.290795-03:00 firewall,info 1727618 - - - 1727618 customlog: in:VLAN99 out:ether2_WAN_Intercorp, src-mac 50:8e:49:7f:b1:68, proto TCP (ACK,FIN), 10.59.0.8:37438->142.251.129.163:443, NAT (10.59.0.8:37438->189.28.49.7:37438)->142.251.129.163:443, len 52\n\n" + "<13>1 2022-05-17T09:18:05.103720-03:00 firewall,info 620254 - - - 620254 customlog: in:VLAN99 out:ether2_WAN_Intercorp, src-mac d0:04:01:8a:ee:7f, proto UDP, 10.59.0.9:42331->172.217.173.110:443, NAT (10.59.0.9:42331->189.28.49.7:42331)->172.217.173.110:443, len 743\n"; final Pattern pattern = Pattern.compile(regex); final Matcher matcher = pattern.matcher(string); if (matcher.find()) { System.out.println("Full match: " + matcher.group(0)); for (int i = 1; i <= matcher.groupCount(); i++) { System.out.println("Group " + i + ": " + matcher.group(i)); } } } }

Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for Java, please visit: https://docs.oracle.com/javase/7/docs/api/java/util/regex/Pattern.html