How can I use named capturing groups in Java regular expressions?

Named grouping in Java

The java.regex package in Java does not support named grouping. Java 7 and higher

Java 7 and higher now supports named grouping. Named groups can be defined using:

Named groups can be referenced using:

<code class="java">(?<name>capturing text)</code>

k: back-referencing a named group

Matcher.group(String name): Returns the captured input subsequence according to the given named group
• ${name} in Matcher.replaceAll(): References the matcher to replace the captured group in the string
• Alternatives (for versions prior to Java 7)

For versions prior to Java 7, the following alternatives are available:

Google named-regex

: A lightweight library that provides support for named grouping.
• jregex
: A feature-rich regular expression library, including support for named groupings.
Custom implementation

You can also support named grouping by writing your own version of Regex. For example, the Regex2 library provides this support.

Example

Example of regular expression using named grouping:

Example of Java code using named grouping:

(?<login>\w+) (?<id>\d+)

Example of using named grouping to replace text:

Pattern pattern = Pattern.compile("(?<login>\w+) (?<id>\d+)");
Matcher matcher = pattern.matcher("TEST 123");

if (matcher.find()) {
  String login = matcher.group("login");
  String id = matcher.group("id");
}

Example of using named grouping backreference:

<code class="java">String result = matcher.replaceAll("aaaaa__sssss_____");</code>

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