Unicode Script Code (ISO 15924) Regex for Java

What this pattern does

This page provides a lightweight, single-purpose regular expression for matching unicode script code (iso 15924), ported and verified for Java. A rigorously tested regex reduces debugging time and protects your application from edge-case failures. The snippet below is ready to drop into your Java project — whether you're validating in a Spring Boot controller, a Jakarta EE service, or a standalone utility class.

Java Implementation

// Unicode Script Code (ISO 15924)
// ReDoS-safe | RegexVault — Localization > Locale & Language

import java.util.regex.Pattern;

public class UnicodeScriptCodeIso15924Validator {
    private static final Pattern PATTERN =
        Pattern.compile("^[A-Z][a-z]{3}$");

    public static boolean validate(String input) {
        return PATTERN.matcher(input).matches();
    }

    // Example
    public static void main(String[] args) {
        System.out.println(validate("Latn")); // true
    }
}

Test Cases

When to use this pattern

This pattern is drawn from the Localization > Locale & Language category and carries a ReDoS-safe certification. That matters for Java developers because critical in Java applications since the JVM regex engine uses backtracking and is susceptible to ReDoS without careful pattern design. RegexVault audits patterns against known backtracking attack vectors, ensuring you have the necessary context before using this regex in a high-stakes production environment.

Common Pitfalls

Technical Notes

ISO 15924 script codes: Latn=Latin, Hans=Simplified Chinese, Hant=Traditional Chinese, Arab=Arabic, Cyrl=Cyrillic, Deva=Devanagari (Hindi), Hang=Hangul, Jpan=Japanese (Han+Hiragana+Katakana). Used in BCP 47 language tags.