Java Logging Best Practices
Implement effective Java logging following standardized frameworks, meaningful log levels, core practices (parameterized logging, exception handling, no sensitive data), flexible configuration, security-conscious logging, monitoring and alerting, and comprehensive logging validation through testing.
What is covered in this Skill?
- Standardized framework selection: SLF4J facade with Logback or Log4j2
- Meaningful and consistent log levels: ERROR, WARN, INFO, DEBUG, TRACE
- Core practices: parameterized logging, proper exception handling, avoiding sensitive data
- Configuration: environment-specific (logback.xml, log4j2.xml), output formats, log rotation
- Security: mask sensitive data, control log access, secure transmission, GDPR/HIPAA compliance
- Log monitoring and alerting: centralized aggregation (ELK, Splunk, Loki), automated alerts
- Logging validation through testing: assert log messages, verify formats, test levels, measure performance impact
Scope: The reference is organized by examples (good/bad code patterns) for each core area. Apply recommendations based on applicable examples.
Constraints
Before applying any logging recommendations, ensure the project compiles. Compilation failure is a blocking condition. After applying improvements, run full verification.
- MANDATORY: Run
./mvnw compile or mvn compile before applying any change
- SAFETY: If compilation fails, stop immediately — do not proceed until resolved
- VERIFY: Run
./mvnw clean verify or mvn clean verify after applying improvements
- BEFORE APPLYING: Read the reference for detailed good/bad examples, constraints, and safeguards for each logging pattern
When to use this skill
- Review Java code for logging and observability
- Apply best practices for logging and observability in Java code
Reference
For detailed guidance, examples, and constraints, see references/180-java-observability-logging.md.
1---2name: 180-java-observability-logging3description: Use when you need to implement or improve Java logging and observability — including selecting SLF4J with Logback/Log4j2, applying proper log levels (ERROR, WARN, INFO, DEBUG, TRACE), parameterized logging, secure logging without sensitive data exposure, environment-specific configuration, log aggregation and monitoring, or validating logging through tests. Part of the skills-for-java project4license: Apache-2.05---6# Java Logging Best Practices78Implement effective Java logging following standardized frameworks, meaningful log levels, core practices (parameterized logging, exception handling, no sensitive data), flexible configuration, security-conscious logging, monitoring and alerting, and comprehensive logging validation through testing.910**What is covered in this Skill?**1112- Standardized framework selection: SLF4J facade with Logback or Log4j213- Meaningful and consistent log levels: ERROR, WARN, INFO, DEBUG, TRACE14- Core practices: parameterized logging, proper exception handling, avoiding sensitive data15- Configuration: environment-specific (logback.xml, log4j2.xml), output formats, log rotation16- Security: mask sensitive data, control log access, secure transmission, GDPR/HIPAA compliance17- Log monitoring and alerting: centralized aggregation (ELK, Splunk, Loki), automated alerts18- Logging validation through testing: assert log messages, verify formats, test levels, measure performance impact1920**Scope:** The reference is organized by examples (good/bad code patterns) for each core area. Apply recommendations based on applicable examples.2122## Constraints2324Before applying any logging recommendations, ensure the project compiles. Compilation failure is a blocking condition. After applying improvements, run full verification.2526- **MANDATORY**: Run `./mvnw compile` or `mvn compile` before applying any change27- **SAFETY**: If compilation fails, stop immediately — do not proceed until resolved28- **VERIFY**: Run `./mvnw clean verify` or `mvn clean verify` after applying improvements29- **BEFORE APPLYING**: Read the reference for detailed good/bad examples, constraints, and safeguards for each logging pattern3031## When to use this skill3233- Review Java code for logging and observability34- Apply best practices for logging and observability in Java code3536## Reference3738For detailed guidance, examples, and constraints, see [references/180-java-observability-logging.md](references/180-java-observability-logging.md).
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