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

r"
"
gm

Test String

Substitution

Processing...

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 = "^(crypto pki certificate chain TP-self-signed-.*)(?:\\n(?!\\1).*)*\\n\\1"; final String string = "test 1 \n" + "crypto pki certificate chain TP-self-signed-1357590403\n" + " +30820330 30820218 A0030201 02020101 300D0609 2A864886 F70D0101 05050030\n" + " +31312F30 2D060355 04031326 494F532D 53656C66 2D536967 6E65642D 43657274\n" + " +69666963 6174652D 31333537 35393034 3033301E 170D3139 30313234 31353436\n" + " +34345A17 0D323030 31303130 30303030 305A3031 312F302D 06035504 03132649\n" + " +4F532D53 656C662D 5369676E 65642D43 65727469 66696361 74652D31 33353735\n" + " +39303430 33308201 22300D06 092A8648 86F70D01 01010500 0382010F 00308201\n" + " +0A028201 0100E69D C133454E 401E763A 7686E453 5D58020D 0E6E122F A0F19E15\n" + " +E0975148 666110BD C1F09B86 CB701C20 EF85E024 F759A921 D11DA10C A13BA3BD\n" + " +20006387 917287CE EA0CFDDC 2FA5DD07 E5B200F4 108CACA1 DCEF0E4E EEE908ED\n" + " +2ACD693B FC90A24F 9F865CB9 859FEFB0 EB8904D4 8FA83D29 E93B892F 32F3EC7D\n" + " +EAA2850E 1793BBCE 86EA47B2 15645634 D81EA89C 1C2BC092 766DF58F 0B289A82\n" + " +0C92E551 7AA9588E F5B41A41 6DB4C785 101E674D BBBCFB42 9F4F9A25 70389515\n" + " +D1C07E2F 18C0557D 95283E90 3CCD2966 5EBF5668 A6B0B847 0B278906 E5BFA668\n" + " +EFBE938A BE70C4C0 1A8D7218 71463EA5 49540A45 DF307B4C 459E657D C039BB68\n" + " +F047B0B2 2F250203 010001A3 53305130 0F060355 1D130101 FF040530 030101FF\n" + " +301F0603 551D2304 18301680 141FADF3 CC2C2293 810EDAA8 9E55327C D2B7D88A\n" + " +88301D06 03551D0E 04160414 1FADF3CC 2C229381 0EDAA89E 55327CD2 B7D88A88\n" + " +300D0609 2A864886 F70D0101 05050003 82010100 91E63F44 376F91C1 C50C08E4\n" + " +B29B902B B1BC7831 C5607897 030835A6 108FC1F2 6F3DEE23 EF3E8FFF 81A121B5\n" + " +26596004 F8F61DFD 1B603C5D 42D850E6 439C7CAE BFC285AE 3FD83870 125594C0\n" + " +51EAAC09 BF42446F C6399B90 D0E10ACA B208819B 645BECE5 DBDDA9AD EBA1FCD9\n" + " +2B14D0DE AB2AC1BF FF064076 ADBB4540 17AB77A4 C6B0DA3B 1BC0F5B8 44030E7B\n" + " +27318CEE 14C90739 DD8684A8 9346EEC1 3F4958EF 835BA822 F58523C9 E9F83105\n" + " +D3E68700 20DAFC5E B1B8CF5B BAC5CEB3 00321088 43125173 51FC8006 270731E6\n" + " +0E0C6183 68BABA99 BD9F4F28 1EDA82D4 F00F1359 F30B6501 BC468C89 49111AB2\n" + " +CBDE5A9D DB8DB33A 45FE6C96 7D49A70F 4C299618\n" + "crypto pki certificate chain TP-self-signed-1357590403\n" + "test 2"; final String subst = ""; final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE); final Matcher matcher = pattern.matcher(string); // The substituted value will be contained in the result variable final String result = matcher.replaceAll(subst); System.out.println("Substitution result: " + result); } }

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