Single line Java logging

You can download the latest jar for use in your project.

Before Java Logging API became part of the JDK (1.4) the de facto standard was the Log4J logging library. It was customizable, easy to setup and configure.

Along came Java 1.4 and the new Java Logging API. Somewhat clumsy and much harder to configure or customize, it has not changed over the course of the subsequent releases.

One of the most annoying things about it was that out of the box it would write out the log message on two lines:

Jun 11, 2009 9:11:21 PM com.letor.example.logging.StandardTest 
INFO: Line 1
Jun 11, 2009 9:11:21 PM com.letor.example.logging.StandardTest 
INFO: Line 2
Jun 11, 2009 9:11:21 PM com.letor.example.logging.StandardTest 
INFO: Line 3

Now, I don't know about you, but I find this very hard on my eyes. It is much harder to get a feel for how many messages were printed, what is the difference between them and is significantly harder to spot what you are looking for.

To rectify this, we can use the following simple, single-line formatter.

You will need to pass the configuration file location as a VM argument to your application.

java -Djava.util.logging.config.file=src/logging.properties your.package.YourApplication

Running this will result in the following output

info: 21:25:00 [main] example.logging.StandardTest   Line 1
info: 21:25:00 [main] example.logging.StandardTest   Line 2
info: 21:25:00 [main] example.logging.StandardTest   Line 3

Now that's much nicer! Feel free to modify the Java file to your preferred format.

The SingleLineFormatter is also capable of logging thrown exceptions and nested exceptions. Here is an example output:

info: 11 Jun 21:29:03 [main] example.logging.Test   Nice, clean single line output
severe: 11 Jun 21:29:03 [main] example.logging.Test   Divided by zero
java.lang.ArithmeticException - / by zero
	at com.letor.example.logging.Test.(Test.java:21)
	at com.letor.example.logging.Test.main(Test.java:37)

severe: 11 Jun 21:29:03 [main] example.logging.Test   Nested operation threw an exception
java.lang.RuntimeException - Parent exception
	at com.letor.example.logging.Test.(Test.java:26)
	at com.letor.example.logging.Test.main(Test.java:37)

java.lang.ArithmeticException - / by zero
	at com.letor.example.logging.Test.(Test.java:21)
	at com.letor.example.logging.Test.main(Test.java:37)

Hopefully this will your Java Logging experience.

For tweaking the output please consult the attached logging.properties file.