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
  • Non-capturing group
    (?:...)
  • Capturing group
    (...)
  • 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

/
/
gm

Test String

Code Generator

Language

Generated Code

import java.util.regex.Matcher; import java.util.regex.Pattern; public class Example { public static void main(String[] args) { final String regex = "^(?<timestamp>\\d+-\\d+-\\d+T\\d+:\\d+:\\d+\\.\\d+([+-])\\d+:\\d+)\\s+\\[(?<severity>\\w+)\\](?<message>.*(?:\\n(?!\\d+-\\d+-\\d+T).*)*)$"; final String string = "2022-06-27T15:22:35.506+00:00 [Info] MSAT starting with 60000 tick ...\n" + "2022-06-27T15:22:35.506+00:00 [Info] pram[:9999] starting ...\n" + "2022-06-27T15:22:35.508+00:00 [Info] New settings received: \n" + "{\"indexer.settings.compaction.days_of_week\":\"Sunday,Monday,Tuesday,Wednesday,Thursday,Friday,Saturday\",\"indexer.settings.compaction.interval\":\"00:00,00:00\",\"indexer.settings.compaction.compaction_mode\":\"circular\",\"indexer.settings.log_level\":\"info\",\"indexer.settings.persisted_snapshot.interval\":5000,\"indexer.settings.compaction.min_frag\":30,\"indexer.settings.inmemory_snapshot.interval\":200,\"indexer.settings.max_cpu_percent\":0,\"indexer.settings.storage_mode\":\"forestdb\",\"indexer.settings.recovery.max_rollbacks\":5,\"indexer.settings.memory_quota\":1073741824,\"indexer.settings.compaction.abort_exceed_interval\":false}\n" + "2022-06-27T15:22:35.508+00:00 [Info] PROJ[:9999] settings notifier from metakv\n"; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); while (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