I use a legacy library that writes logs using log4j. My default log4j.properties file directs the log to the console, but in some specific functions of my main program, I would
Add the following to your log file
log4j.logger.com.class.with.package.BasicImplementation = off, logfiledata
log4j.appender.logfiledata = ac.biu.nlp.nlp.log.BackupOlderFileAppender
log4j.appender.logfiledata.append=false
log4j.appender.logfiledata.layout = org.apache.log4j.PatternLayout
log4j.appender.logfiledata.layout.ConversionPattern = %-5p %d{HH:mm:ss} [%t]: %m%n
log4j.appender.logfiledata.File = logfiledata.log
If the above will not stop if from logging, it will at least log all the data from BasicImplementation class to a separate file.