Good examples using java util logging

Question

I want to use logs in my program  I heard about java util logging  but I don t know how to begin   Are there any examples of what can I do with logging  How would I use logging in my own program

User · Answer

There are many examples and also of different types for logging. Take a look at the java.util.logging package.

Example code:

import java.util.logging.Logger;

public class Main {

  private static Logger LOGGER = Logger.getLogger("InfoLogging");

  public static void main(String[] args) {
    LOGGER.info("Logging an INFO-level message");
  }
}

Without hard-coding the class name:

import java.util.logging.Logger;

public class Main {
  private static final Logger LOGGER = Logger.getLogger(
    Thread.currentThread().getStackTrace()[0].getClassName() );

  public static void main(String[] args) {
    LOGGER.info("Logging an INFO-level message");
  }
}

User · Answer

I would suggest that you use Apache s commons logging utility  It is highly scalable and supports separate log files for different loggers  See here

User · Answer

I d use minlog  personally  It s extremely simple  as the logging class is a few hundred lines of code

User · Answer

java util logging keeps you from having to tote one more jar file around with your application  and it works well with a good Formatter     In general  at the top of every class  you should have   private static final Logger LOGGER   Logger getLogger  ClassName class getName        Then  you can just use various facilities of the Logger class     Use Level FINE for anything that is debugging at the top level of execution flow   LOGGER log  Level FINE   processing  0  entries in loop   list size          Use Level FINER   Level FINEST inside of loops and in places where you may not always need to see that much detail when debugging basic flow issues   LOGGER log  Level FINER   processing  0     1    new Object    i  list get i         Use the parameterized versions of the logging facilities to keep from generating tons of String concatenation garbage that GC will have to keep up with  Object   as above is cheap  on the stack allocation usually     With exception handling  always log the complete exception details   try          something that can throw an ignorable exception   catch  Exception ex         LOGGER log  Level SEVERE  ex toString    ex        I always pass ex toString   as the message here  because then when I  grep -n  for  Exception  in log files  I can see the message too  Otherwise  it is going to be on the next line of output generated by the stack dump  and you have to have a more advanced RegEx to match that line too  which often gets you more output than you need to look through

User · Answer

Should declare logger like this   private final static Logger LOGGER   Logger getLogger MyClass class getName       so if you refactor your class name it follows   I wrote an article about java logger with examples here

User · Answer

SLF4J is a better logging facade than Apache Commons Logging  ACL   It has bridges to other logging frameworks  making direct calls to ACL  Log4J  or Java Util Logging go through SLF4J  so that you can direct all output to one log file if you wish  with just one log configuration file  Why would your application use multiple logging frameworks  Because 3rd-party libraries you use  especially older ones  probably do   SLF4J supports various logging implementations  It can output everything to standard-out  use Log4J  or Logback  recommended over Log4J    http   www slf4j org   http   logback qos ch

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