Log formatters format log messages so they can be used by various log handlers.
Handlers can be configured with a log formatter that knows how to format log records. The event, which is represented by the log record object, is passed to the appropriate formatter by the handler. The formatter returns formatted output to the handler, which writes the output to the output device.
The formatter is responsible for rendering the event for output. This formatter uses the resource bundle that is specified in the event to look up the message in the appropriate language.
Formatters are attached to handlers using the setFormatter method.
You can find the java.util.logging documentation at http://java.sun.com/j2se/.