Introduction

It's easy, but I'll show you how to use log4j 2.0 as a reminder. Investigate for use when creating small Java apps.

Maven dependency definition

Added log4j to Maven used for library management

`pom.xml`


<dependencies>
	<dependency>
		<groupId>org.apache.logging.log4j</groupId>
		<artifactId>log4j-api</artifactId>
		<version>2.10.0</version>
	</dependency>
	<dependency>
		<groupId>org.apache.logging.log4j</groupId>
		<artifactId>log4j-core</artifactId>
		<version>2.10.0</version>
	</dependency>
</dependencies>

Create configuration file

Set to output logs to standard output.

`log4j2.xml`


<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE project>
<Configuration status="off">
	<Properties>
		<Property name="format1">%d{yyyy/MM/dd HH:mm:ss.SSS} [%t] %-6p %c{10} %m%n</Property>
	</Properties>
	<Appenders>
		<Console name="Console" target="SYSTEM_OUT">
			<PatternLayout>
				<pattern>${format1}</pattern>
			</PatternLayout>
		</Console>
	</Appenders>

	<Loggers>
		<Root level="trace">
			<AppenderRef ref="Console" />
		</Root>
	</Loggers>
</Configuration>

Implementation

The name of the logger should just be copied and pasted using lookup.

public class Hoge {
  private static final Logger logger = LogManager.getLogger(MethodHandles.lookup().lookupClass());
  
  public void sayHoge() {
    logger.info("hoge hoge");
  }
}

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