Log4j2: PatternLayout: format log message

This is the widely used layout, format log messages using pattern string. The format of the results is depend on the pattern string you used.

Each conversion specifier starts with a percent sign (%) and is followed by optional format modifiers and a conversion character. The conversion character specifies the type of data, e.g. category, priority, date, thread name. The format modifiers control such things as field width, padding, left and right justification.

For Example,

pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n"

Go through following link for more information about PatternLayout.

https://logging.apache.org/log4j/2.0/manual/layouts.html

log4j2.xml

<?xml version="1.0" encoding="UTF-8"?>
<Configuration status="warn" name="MyApp" packages="">
 <Appenders>
  <Console name="my_console_appender" target="SYSTEM_OUT">
   <PatternLayout pattern="%d{HH:mm:ss.SSS} [%t] %-5level %logger{36} - %msg%n" />
  </Console>

 </Appenders>

 <Loggers>
  <Root level="info">
   <AppenderRef ref="my_console_appender" />
  </Root>
 </Loggers>
</Configuration>

package log4j_tutorial;

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

public class HelloWorld {
 private static final Logger logger = LogManager.getLogger();

 public static void main(String args[]) throws InterruptedException {
  int val1 = 10, val2 = 11, val3 = 12;

  logger.trace("val1={}, val2={}, val3={}", val1, val2, val3);
  logger.debug("val1={}, val2={}, val3={}", val1, val2, val3);
  logger.info("val1={}, val2={}, val3={}", val1, val2, val3);
  logger.warn("val1={}, val2={}, val3={}", val1, val2, val3);
  logger.error("val1={}, val2={}, val3={}", val1, val2, val3);
  logger.fatal("val1={}, val2={}, val3={}", val1, val2, val3);

 }

}

Run HelloWorld application, you will get following messages in console.

11:46:51.973 [main] INFO  log4j_tutorial.HelloWorld - val1=10, val2=11, val3=12
11:46:51.974 [main] WARN  log4j_tutorial.HelloWorld - val1=10, val2=11, val3=12
11:46:51.974 [main] ERROR log4j_tutorial.HelloWorld - val1=10, val2=11, val3=12
11:46:51.974 [main] FATAL log4j_tutorial.HelloWorld - val1=10, val2=11, val3=12

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