Java Logging: Log Levels

Table of Contents

• Filtering Messages

When a message is logged via a Logger it is logged with a certain log level. The built-in log levels are:

• SEVERE
• WARNING
• INFO
• CONFIG
• FINE
• FINER
• FINEST

The log level is represented by the class java.util.logging.Level. This class contains a constant for each of the above log levels. It is one of these constants you use when you log a message to a Logger. Here is an example:

logger.log(Level.SEVERE, "A severe message!");

Filtering Messages

You can filter the messages by their log level, meaning you can configure a Logger to not log, and not propagate messages below a certain level. Here is an example of that:

logger.setLevel(Level.WARNING);

The Logger now ignores all messages below the log level WARNING.

To understand how log levels behave in the Logger hierarchy, check out the text on the Logger hierarchy.