Question

I want to use the new Log4J 2 – Java Logging Framework. Everything work fine, but I tried since a hour to load a custom configuration file to configure the logging (like log level).

This is my log4j2.xml:

<?xml version="1.0" encoding="UTF-8"?>
<configuration status="OFF">
  <appenders>
    <Console name="Console" target="SYSTEM_OUT">
      <PatternLayout pattern="%d{HH:mm:ss} [%t] %-5level %logger{36} - %msg%n"/>
    </Console>
  </appenders>
  <loggers>
    <root level="error">
      <appender-ref ref="Console"/>
    </root>
  </loggers>
</configuration>

I tried the following, but nothing works:

• Move the log4j2.xml file so it’s located in the default package.
• Move the log4j2.xml file anywhere in the project
• Name the log4j2.xml file as “log4j.xml”
• Create a folder in your project, place your log4j2.xml file there and add that folder to your runtime classpath

Since the official website can’t help me, I hope you can help me get Log4j 2 working with my configuration file.

Answer 1

Important: make sure the name of the configuration file is log4j2.xml (note the 2 before the period) as opposed to log4j.xml

My guess is nothing’s happening because nothing is logged using the error level. You may want to try adding another logger like so:

<logger name="com.foo.Bar" level="trace">
  <appender-ref ref="Console"/>
</logger>

Looks like the Configuration section might be a good resource.

To elaborate further, you’re specifying a logger with the level set to “error”:

<root level="error">
  <appender-ref ref="Console"/>
</root>

This means that only the messages logged using Level.ERROR will show up in the log. Adding a logger with a less restrictive level will allow for more messages to appear in the log. I recommend taking a look at the Architecture section of the manual (if you scroll down the page you’ll see the table that explains logging levels). Alternatively, you could just change the level of the root logger to trace (instead of adding a new logger)

Given the configuration you specified, executing the code below yields something like 13:27:50.244 [main] ERROR com.example.Log4j2Tester - testing ERROR level

package com.example;

import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

public class Log4j2Tester {
    private static final Logger LOG = LogManager.getLogger(Log4j2Tester.class);

    public static void main(String[] args) {
        LOG.error("testing ERROR level");

//if you change the level of root logger to 'trace'
//then you'll also see something like
//    13:27:50.244 [main] TRACE com.example.Log4j2Tester - exiting application
        LOG.trace("exiting application");
    }
}