Where does the slf4j log file get saved

Question

I have the followed imports   import org slf4j Logger  import org slf4j LoggerFactory    and the following instantiation   private static Logger logger   LoggerFactory getLogger Test class     and the following in my Main method   logger info  SOME MESSAGE        However  I m not able to find the output anywhere  All I see is that in my console there is   21 21 24 235  main  INFO  some folder Test - SOME MESSAGE     How do I locate the log file   Note that the following are on my  build path   slf4j-api-1 7 5 jar  slf4j-log4j12-1 6 4 jar  I read the answer to similar questions but nobody actually says how to fix the problem

User · Answer

The log file is not visible because the slf4j configuration file location needs to passed to the java run command using the following arguments .(e.g.)

-Dlogging.config={file_location}\log4j2.xml

or this:

-Dlog4j.configurationFile={file_location}\log4j2.xml

User · Answer

It does not write to a file by default  You would need to configure something like the RollingFileAppender and have the root logger write to it  possibly in addition to the default ConsoleAppender

User · Answer

slf4j is only an API  You should have a concrete implementation  for example log4j   This concrete implementation has a config file which tells you where to store the logs     When slf4j catches a log messages with a logger  it is given to an appender which decides what to do with the message  By default  the ConsoleAppender displays the message in the console   The default configuration file is     lt  xml version  1 0  encoding  UTF-8   gt   lt Configuration status  WARN  gt      lt Appenders gt       lt  -- By default   gt  console -- gt       lt Console name  Console  target  SYSTEM OUT  gt         lt PatternLayout pattern   d HH mm ss SSS    t   -5level  logger 36  -  msg n   gt       lt  Console gt     lt  Appenders gt      lt Loggers gt       lt Root level  error  gt         lt AppenderRef ref  Console   gt       lt  Root gt     lt  Loggers gt   lt  Configuration gt    If you put a configuration file available in the classpath  then your concrete implementation  in your case  log4j  will find and use it  See Log4J documentation   Example of file appender     lt Appenders gt   lt File name  File  fileName    filename   gt     lt PatternLayout gt       lt pattern gt  d  p  C 1     t   m n lt  pattern gt     lt  PatternLayout gt   lt  File gt        lt  Appenders gt    Complete example with a file appender      lt  xml version  1 0  encoding  UTF-8   gt   lt Configuration status  WARN  gt      lt Appenders gt       lt File name  File  fileName    filename   gt         lt PatternLayout gt           lt pattern gt  d  p  C 1     t   m n lt  pattern gt         lt  PatternLayout gt       lt  File gt     lt  Appenders gt      lt Loggers gt       lt Root level  error  gt         lt AppenderRef ref  File   gt       lt  Root gt     lt  Loggers gt    lt  Configuration gt

User · Answer

As already mentioned its just a facade and it helps to switch between different logger implementation easily  For example if you want to use log4j implementation   A sample code would looks like below   If you use maven get the dependencies        lt dependency gt           lt groupId gt org slf4j lt  groupId gt           lt artifactId gt slf4j-api lt  artifactId gt           lt version gt 1 7 6 lt  version gt       lt  dependency gt       lt dependency gt           lt groupId gt org slf4j lt  groupId gt           lt artifactId gt slf4j-log4j12 lt  artifactId gt           lt version gt 1 7 5 lt  version gt       lt  dependency gt    Have the below in log4j properties in location src main resources log4j properties              log4j rootLogger DEBUG  STDOUT  file              log4j appender STDOUT org apache log4j ConsoleAppender             log4j appender STDOUT layout org apache log4j PatternLayout             log4j appender STDOUT layout ConversionPattern  5p   t    F  L  -  m n              log4j appender file org apache log4j RollingFileAppender             log4j appender file File mylogs log             log4j appender file layout org apache log4j PatternLayout             log4j appender file layout ConversionPattern  d dd-MM-yyyy HH mm ss   -5p  c 1   L -  m n   Hello world code below would prints in console and to a log file as per above configuration               import org slf4j Logger              import org slf4j LoggerFactory               public class HelloWorld                 public static void main String   args                    Logger logger   LoggerFactory getLogger HelloWorld class                   logger info  Hello World

[java] Where does the slf4j log file get saved?

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