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 single character of: a, b, c or d
    [[ab][cd]]
  • 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]
  • Character class intersection
    [\w&&[^\d]]
  • 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

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 = "^(?:(?:(jdbc)\\:{1})?(?:(\\w+):/{2})?(?:([^@\\/?!\\\"':#\\s]+(?::\\w+)?)@)?)?(?:([^@\\/?!\\\"':#\\s]+(?::\\d+)?)(?=(?:$)|(?:/)))?(?:/([^@?!\\\"':#\\s]*)(?=(?:$)|(?:\\?)))?(?:[?]([^#?!\\s]+))?\\S*$"; final String string = "postgresql://\n" + "postgresql://localhost\n" + "postgresql://localhost:5432\n" + "postgresql://localhost/mydb\n" + "postgresql://user@localhost\n" + "postgresql://user:secret@localhost\n" + "postgresql://user:secret@localhost:1533\n" + "postgresql://user:secret@localhost:1533/\n" + "postgresql://user:secret@localhost:1533/db?\n" + "postgresql://user::se:::cret@localhost::port\n" + "postgresql://user::secret@local::host::po::::rt/dd::b:::b\n" + "postgresql://other@localhost/otherdb?connect_timeout=10&application_name=myapp\n" + "postgresql://localhost/mydb?user=other&password=secret\n" + "jdbc:postgresql://localhost\n" + "jdbc:postgresql://other@localhost/otherdb?connect_timeout=10&application_name=myapp\n" + "jdbc:postgresql://other@localhost:5432/otherdb?connect_timeout=10&application_name=myapp\n" + "jdbc:postgresql://other:pass@localhost:5432/otherdb?connect_timeout=10&application_name=myapp\n" + "jdbc:postgresql://other:pass@localhost:5432/other/db?connect_timeout=10&application_name=myapp\n" + "jdbc:postgresql://other:pass@localhost:5432/other/db??connect_timeout=10&application_name=myapp\n" + "jdbc:postgresql://other::pass@localhost::5432/oth:erdb?connect_timeout=10&application_name=myapp\n" + "\"\"''\":::abc;\n" + "postgresql://127.0.0.1::5432\n" + "127.0.0.1::5432\n" + "localhost\n" + "user@localhost\n" + "user@localhost:1533\n" + "user@localhost:1533/db\n" + "user@localhost:1533/db?\n" + "user:secret@localhost\n" + "user:secret@localhost/db\n" + "user:secret@localhost/db?\n" + "user:secret@local:host/otherdb\n" + "user:secret@local:1533/othe1//db\n" + "user:secret@localhost/otherdb?connect_timeout=10&application_name=myapp\n" + "user:secret@localhost/other/db?connect_timeout=10&application_name=myapp\n" + "user:secret@localhost/other/db??connect_timeout=10&application_name=myapp\n" + "us\"\"er:se::cret@loca''lhost\n" + "user:secret@local:1533/otherdb\n" + "jdbc:postgresql://user:secret@localhost:1533/otherdb\n" + "jdbc:postgresql://user:secret@@localhost:1533/otherdb\n" + "jdbc:postgresql://user:secret@localhost:1533/otherdb?\n" + "jdbc:postgresql://:secret@localhost:1533/otherdb?\n" + "jdbc:postgresql://user:secret@:1533/otherdb?\n" + "jdbc:postgresql://user:secret@localhost:1533/@otherdb?\n" + "jdbc:postgresql://user:secret@localhost/otherdb?connect_timeout=10&application_name=myapp\n" + "jdbc:postgresql://user:secret@localhost:1533/otherdb?connect_timeout=10&application_name=myapp\n" + "jd''bc:post\"\"gresql://us..er:sec,,ret@localh++ost/ot+-herdb?connect_timeout=10&application_name=myapp"; final String subst = "$1 \\n$2 \\n$3 \\n$4 \\n$5 \\n---\\n"; 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