Exceptions and Logging - Java 8 Recipes - page 334

Table 9-1 . Logging Levels

Logging
Level

Recommendation

Least important of the logging events

Trace

Debug Use for extra information that helps with debugging

Use for everyday logging messages

Info

Use for recoverable issues, or where the suspicions of a wrong setting/nonstand-
ard behavior happens

Warn

Use for exceptions, actual errors, and things that you really need to know

Error

Fatal Most important

Note When setting the log level, loggers will log at that level and below. Therefore,
if a logging configuration sets the log level to info , messages at the Info , Warn , Er-
ror , and Fatal levels will be logged.

9-10. Rotating and Purging Logs
Problem

You have started to log information, but the information logged continues growing out
of control. You would like to keep only the last 250KB worth of log entries within your
log files.

Solution

Use SLF4J with java.util.logging to configure rolling logs. In this example, a
logger named recipeLogger is used to log many messages. The output will pro-
duce rolled log files with the most recent logged information in the important Lo-
g0.log file.

loadLoggingConfiguration();