Log Level Detection Regex for Java

What this pattern does

This page provides a well-structured, multi-part regular expression for matching log level detection, 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

// Log Level Detection
// ReDoS-safe | RegexVault — Dev & Systems > Log Parsing

import java.util.regex.Pattern;

public class LogLevelDetectionValidator {
    private static final Pattern PATTERN =
        Pattern.compile("\\b(TRACE|DEBUG|INFO|WARN(?:ING)?|ERROR|FATAL|CRITICAL|NOTICE|SEVERE)\\b");

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

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

Test Cases

When to use this pattern

This pattern is drawn from the Dev & Systems > Log Parsing 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

The \b word boundaries prevent partial matches (INFORMATION matching as INFO). Capture group 1 contains the matched level. Normalize to a canonical set for cross-framework analysis.