How to enable Logger.debug() in Log4j

java log4j
Hariharbalaji picture Hariharbalaji · Nov 4, 2009 · Viewed 211.5k times · Source

While trying to execute the following lines only the last two statements are displayed("Here is some ERROR" and "Here is some FATAL") and the first three statements are not displayed.I had just started to learn this topic, can anyone tell why is this happening?

    logger.debug("Here is some DEBUG");
    logger.info("Here is some INFO");
    logger.warn("Here is some WARN");
    logger.error("Here is some ERROR");
    logger.fatal("Here is some FATAL");

the log4j.property has 

log4j.rootLogger=debug,stdout
log4j.appender.stdout=org.apache.log4j.ConsoleAppender
log4j.appender.stdout.Target=System.out
log4j.appender.stdout.layout=org.apache.log4j.PatternLayout
log4j.appender.stdout.layout.ConversionPattern=[%5p] %d{mm:ss}(%F:%M:%L)%n%m%n%n

Answer

Thomas Lötzer picture Thomas Lötzer · Nov 4, 2009

You probably have a log4j.properties file somewhere in the project. In that file you can configure which level of debug output you want. See this example:

log4j.rootLogger=info, console

log4j.appender.console=org.apache.log4j.ConsoleAppender
log4j.appender.console.layout=org.apache.log4j.PatternLayout
log4j.appender.console.layout.ConversionPattern=%-4r [%t] %-5p %c %x - %m%n

log4j.logger.com.example=debug

The first line sets the log level for the root logger to "info", i.e. only info, warn, error and fatal will be printed to the console (which is the appender defined a little below that).

The last line sets the logger for com.example.* (if you get your loggers via LogFactory.getLogger(getClass())) will be at debug level, i.e. debug will also be printed.

Related questions

No appenders could be found for logger(log4j)?

I have put log4j to my buildpath, but I get the following message when I run my application: log4j:WARN No appenders could be found for logger (dao.hsqlmanager). log4j:WARN Please initialize the log4j system …

Read More
Where should I put the log4j.properties file?

I wrote a web service project using netbeans 6.7.1 with glassfish v2.1, put log4j.properties to the root dir of project and use: static Logger logger = Logger.getLogger(MyClass.class); in Constructor: PropertyConfigurator.configure("log4j.properties"); and in functions: …

Read More
log4j:WARN No appenders could be found for logger in web.xml

I already put the log4jConfigLocation in web.xml, but I still get the following warning: log4j:WARN No appenders could be found for logger ⤦ ⤥ (org.springframework.web.context.ContextLoader). log4j:WARN Please initialize the log4j system …

Read More