slf4j: how to log formatted message, object array, exception slf4j: how to log formatted message, object array, exception java java

slf4j: how to log formatted message, object array, exception


As of SLF4J 1.6.0, in the presence of multiple parameters and if the last argument in a logging statement is an exception, then SLF4J will presume that the user wants the last argument to be treated as an exception and not a simple parameter. See also the relevant FAQ entry.

So, writing (in SLF4J version 1.7.x and later)

 logger.error("one two three: {} {} {}", "a", "b",               "c", new Exception("something went wrong"));

or writing (in SLF4J version 1.6.x)

 logger.error("one two three: {} {} {}", new Object[] {"a", "b",               "c", new Exception("something went wrong")});

will yield

one two three: a b cjava.lang.Exception: something went wrong    at Example.main(Example.java:13)    at java.lang.reflect.Method.invoke(Method.java:597)    at ...

The exact output will depend on the underlying framework (e.g. logback, log4j, etc) as well on how the underlying framework is configured. However, if the last parameter is an exception it will be interpreted as such regardless of the underlying framework.


In addition to @Ceki 's answer, If you are using logback and setup a config file in your project (usually logback.xml), you can define the log to plot the stack trace as well using

<encoder>    <pattern>%date |%-5level| [%thread] [%file:%line] - %msg%n%ex{full}</pattern> </encoder>

the %ex in pattern is what makes the difference