Severity classifies log messages by their importance to an investigation. It helps separate critical failures from routine events and fine-grained execution details. section 4.2.2
Use common severity levels to control attention and log volume:
- Error marks a critical issue that should always be logged, commonly an unhandled exception. section 4.2.2
- Warn records a potentially failed event that the application handled, such as a successful retry. section 4.2.2
- Info records common events that describe the application's main execution. section 4.2.2
- Debug provides fine-grained details and is usually enabled only when other messages are insufficient. section 4.2.2
String digit extraction
A StringDigitExtractor logs the extraction start and result at info, while logging each parsed character at debug. An info root logger shows only summary events; changing it to debug reveals the character-level trace.
