Why are the Level FINE logging messages not showing

Question

The JavaDocs for java util logging Level state     The levels in descending order are    SEVERE  highest value  WARNING INFO CONFIG FINE FINER FINEST  lowest value       Source  import java util logging     class LoggingLevelsBlunder        public static void main String   args            Logger logger   Logger getAnonymousLogger            logger setLevel Level FINER           System out println  Logging level is      logger getLevel             for  int ii 0  ii lt 3  ii                  logger log Level FINE  ii          ii ii                logger log Level INFO  ii          ii ii                        Output  Logging level is  FINER Jun 11  2011 9 39 23 PM LoggingLevelsBlunder main INFO  0 0 Jun 11  2011 9 39 24 PM LoggingLevelsBlunder main INFO  1 1 Jun 11  2011 9 39 24 PM LoggingLevelsBlunder main INFO  2 4 Press any key to continue         Problem statement  My example sets the Level to FINER  so I was expecting to see 2 messages for each loop   Instead I see a single message for each loop  the Level FINE messages are missing    Question  What needs changing in order to see the FINE    FINER or FINEST  output   Update  solution   Thanks to Vineet Reynolds  answer  this version works according to my expectation   It displays 3 x INFO messages   amp  3 x FINE messages   import java util logging     class LoggingLevelsBlunder        public static void main String   args            Logger logger   Logger getAnonymousLogger               LOG this level to the log         logger setLevel Level FINER            ConsoleHandler handler   new ConsoleHandler               PUBLISH this level         handler setLevel Level FINER           logger addHandler handler            System out println  Logging level is      logger getLevel             for  int ii 0  ii lt 3  ii                  logger log Level FINE  ii          ii ii                logger log Level INFO  ii          ii ii

User · Answer

The Why  java util logging has a root logger that defaults to Level INFO  and a ConsoleHandler attached to it that also defaults to Level INFO  FINE is lower than INFO  so fine messages are not displayed by default     Solution 1  Create a logger for your whole application  e g  from your package name or use Logger getGlobal    and hook your own ConsoleLogger to it  Then either ask root logger to shut up  to avoid duplicate output of higher level messages   or ask your logger to not forward logs to root   public static final Logger applog   Logger getGlobal            Create and set handler Handler systemOut   new ConsoleHandler    systemOut setLevel  Level ALL    applog addHandler  systemOut    applog setLevel  Level ALL        Prevent logs from processed by default Console handler  applog setUseParentHandlers  false       Solution 1 Logger getLogger     setLevel  Level OFF       Solution 2     Solution 2  Alternatively  you may lower the root logger s bar   You can set them by code   Logger rootLog   Logger getLogger      rootLog setLevel  Level FINE    rootLog getHandlers   0  setLevel  Level FINE       Default console handler   Or with logging configuration file  if you are using it    level   FINE java util logging ConsoleHandler level   FINE   By lowering the global level  you may start seeing messages from core libraries  such as from some Swing or JavaFX components  In this case you may set a Filter on the root logger to filter out messages not from your program

User · Answer

I found my actual problem and it was not mentioned in any answer  some of my unit-tests were causing logging initialization code to be run multiple times within the same test suite  messing up the logging on the later tests

User · Answer

Tried other variants  this can be proper       Logger logger   Logger getLogger MyClass class getName                 Level level   Level ALL      for Handler h   java util logging Logger getLogger     getHandlers                h setLevel level       logger setLevel level      this must be shown     logger fine  fine        logger info  info

User · Answer

why is my java logging not working  provides a jar file that will help you work out why your logging in not working as expected  It gives you a complete dump of what loggers and handlers have been installed and what levels are set and at which level in the logging hierarchy

User · Answer

WHY  As mentioned by  Sheepy  the reason why it doesn t work is that java util logging Logger has a root logger that defaults to Level INFO  and the ConsoleHandler attached to that root logger also defaults to Level INFO  Therefore  in order to see the FINE    FINER or FINEST  output  you need to set the default value of the root logger and its ConsoleHandler to Level FINE as follows   Logger getLogger     setLevel Level FINE   Logger getLogger     getHandlers   0  setLevel Level FINE      The problem of your Update  solution   As mentioned by  mins  you will have the messages printed twice on the console for INFO and above  first by the anonymous logger  then by its parent  the root logger which also has a ConsoleHandler set to INFO by default  To disable the root logger  you need to add this line of code  logger setUseParentHandlers false    There are other ways to prevent logs from being processed by default Console handler of the root logger mentioned by  Sheepy  e g    Logger getLogger     getHandlers   0  setLevel  Level OFF      But Logger getLogger     setLevel  Level OFF    won t work because it only blocks the message passed directly to the root logger  not the message comes from a child logger  To illustrate how the Logger Hierarchy works  I draw the following diagram      public void setLevel Level newLevel  set the log level specifying which message levels will be logged by this logger  Message levels lower than this value will be discarded  The level value Level OFF can be used to turn off logging  If the new level is null  it means that this node should inherit its level from its nearest ancestor with a specific  non-null  level value

User · Answer

This solution appears better to me  regarding maintainability and design for change    Create the logging property file embedding it in the resource project folder  to be included in the jar file     Logging handlers   java util logging ConsoleHandler  level   ALL    Console Logging java util logging ConsoleHandler level   ALL  Load the property file from code   public static java net URL retrieveURLOfJarResource String resourceName       return Thread currentThread   getContextClassLoader   getResource resourceName      public synchronized void initializeLogger        try  InputStream is   retrieveURLOfJarResource  logging properties   openStream            LogManager getLogManager   readConfiguration is        catch  IOException e

User · Answer

Loggers only log the message  i e  they create the log records  or logging requests   They do not publish the messages to the destinations  which is taken care of by the Handlers  Setting the level of a logger  only causes it to create log records matching that level or higher   You might be using a ConsoleHandler  I couldn t infer where your output is System err or a file  but I would assume that it is the former   which defaults to publishing log records of the level Level INFO  You will have to configure this handler  to publish log records of level Level FINER and higher  for the desired outcome   I would recommend reading the Java Logging Overview guide  in order to understand the underlying design  The guide covers the difference between the concept of a Logger and a Handler   Editing the handler level  1  Using the Configuration file  The java util logging properties file  by default  this is the logging properties file in JRE HOME lib  can be modified to change the default level of the ConsoleHandler   java util logging ConsoleHandler level   FINER   2  Creating handlers at runtime  This is not recommended  for it would result in overriding the global configuration  Using this throughout your code base will result in a possibly unmanageable logger configuration   Handler consoleHandler   new ConsoleHandler    consoleHandler setLevel Level FINER   Logger getAnonymousLogger   addHandler consoleHandler

[java] Why are the Level.FINE logging messages not showing?

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