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JabRef uses the logging facade SLF4j. All log messages are passed internally to tinylog which handles any filtering, formatting and writing of log messages.

Obtaining a logger for a class:

private static final Logger LOGGER = LoggerFactory.getLogger(<ClassName>.class);

Please always use LOGGER.debug for debugging.


String example = "example";
LOGGER.debug("Some state {}", example);

Enable logging in

level@org.jabref.example.ExampleClass = debug

If the logging event is caused by an exception, please add the exception to the log message as:

  catch (SomeException e) {
     LOGGER.warn("Warning text.", e);

When running tests, is used. It is located under src/test/resources. As default, only info is logged. When developing, it makes sense to use debug as log level. One can change the log level per class using the pattern level@class=debug is set to debug. In the .properties file, this is done for org.jabref.model.entry.BibEntry.

Further reading

SLF4J also support parameterized logging, e.g. if you want to print out multiple arguments in a log statement use a pair of curly braces ({}). Head to for examples.