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Questions tagged [log4j]

log4j is a popular Java-based logging utility. It is a project of the Apache Software Foundation and is licensed under The Apache Software License, Version 2.0

Apache Log4j is a Java-based logging utility. It is a project of the Apache Software Foundation. Log4j is one of several Java Logging Frameworks.

Log4j in written in Java and also support cross platform and available with Apache License 2.0 License.

Log4j helps programmers output log statements from their programs. The log statements can be configured to be output to a variety of locations including the console, files and email. Log4j is a hierarchical logging utility which makes it possible to change the granularity at which log statements are output.

It is common practice to use the program's package structure as the basis for the hierarchy since the package structure of an application is inherently hierarchical and usually correlates to the hierarchy of the program code.

Log4j2.x changes the API and is no longer downward compatible to log4j1.x

Official Website:

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Latest release log4j1: 1.2.17 released on August 5, 2015

Latest release log4j2: 2.13.3 released on 2020-05-10

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Java Logging: show the source line number of the caller (not the logging helper method)

The numerous (sigh...) logging frameworks for Java all do a nice job of showing the line number of the source file name for the method that created the log message: log.info("hey"); [INFO] [Foo:413] hey But if have a helper method in between,…
Thilo
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Log4j : Multiple loggers, levels and appenders

I am having trouble with duplicate log messages when writing to multiple log files using log4j. At present I am trying to log INFO level data (and upwards) for the specific logger named foobar in my foo.log file and then all WARN level log messages…
My Head Hurts
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Why calling LoggerFactory.getLogger(...) every time is not recommended?

I've read tons of posts and documents (on this site and elsewhere) pointing that the recommended pattern for SFL4J logging is: public class MyClass { final static Logger logger = LoggerFactory.getLogger(MyClass.class); public void…
danirod
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Where to place log4j.xml

How can we specify where log4j has to look at when trying to find its xml configuration file? It seems that, by default, log4j looks into the root of a class folder, I can say that using the debug log4j functionality and running my application from…
Farid
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Log4j config - different logs to different files

This might be a very easy question for some, but personally I find Log4j config to be nightmarishly difficult and that learning to perform brain surgery might be less challenging. I am trying to lave multiple loggers logging into different…
NickJ
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How do I configure Spring and SLF4J so that I can get logging?

I've got a maven & spring app that I want logging in. I'm keen to use SLF4J. I want to put all my config files into a directory {classpath}/config including log4j.xml and then init using a spring bean. e.g.
Programming Guy
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Getting Exception org.apache.logging.slf4j.SLF4JLoggerContext cannot be cast to org.apache.logging.log4j.core.LoggerContext

My code is very simple using apache-log4j-2.0.2: import org.apache.log4j.BasicConfigurator; import org.apache.log4j.Logger; public class Log4jtest { static Logger log =Logger.getLogger(Log4jtest.class); public static void main(String[] args) { …
user3334466
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Is it possible to configure logback logger levels on the command line?

Log4J allows you to pass the level you'd like particular loggers in your application to log at from the command line, e.g. "-Dlog4j.logger.com.whatever.MyClass=DEBUG". I can't find any similar facility in Logback. According to the FAQ, all it…
bfancher
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log4j.properties file - multiple loggers in same class

I would like to have two different log4j loggers in my application, and for there to be no "overlap" between the content they write to their respect logs. For example: Logger1 writes INFO events related to one set of system events Logger2 writes…
Alex Averbuch
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Configuring RollingFileAppender in log4j

I'm working on a set of web services and we'd like to have a daily rotated log. I'm trying to get org.apache.log4j.rolling.RollingFileAppender from the log4j extras companion working, since the documentation suggests this is best for production…
chrisbunney
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How to turn off debug log messages in spring boot

I read in spring boot docs (https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-logging.html) you can also specify debug=true in your application.properties" So I guess I can turn off the debug logs by adding debug=false…
Jim C
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log4j.properties vs log4j.xml

I was asked to move from properties style configuration to xml style. The process itself is straightforward and it is not causing me any trouble, I was simply curious why I got asked this and I looked for the reason. I found this nice post Why chose…
ThanksForAllTheFish
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In Log4j2, how do I associate an XML Schema with log4j2.xml?

I have been giving the new Log4j2 a go. It seems, from the documentation on migration, that the XML Schema/DTD specification has been done away with. That seems like a step backwards. Surely it should be possible to associate either an XML Schema or…
glts
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Best way to aggregate multiple log files from several servers

I need a simple way to monitor multiple text log files distributed over a number of HP-UX servers. They are a mix of text and XML log files from several distributed legacy systems. Currently we just ssh to the servers and use tail -f and grep, but…
Claes Mogren
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Is Logback also affected by the Log4j zero-day vulnerability issue in Spring Boot?

As I understand it, Logback is written by the same authors. Our applications are using Logback instead. Is there a chance that Logback is also affected by the exploit in Log4j? This is critical for our organisation.
saran3h
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