How to Log in a Scala Application

1. Use the logger Class to Do Logging in a Scala Application
2. Levels of Logging in Scala

This article will introduce how to do application logging in Scala.

Use the logger Class to Do Logging in a Scala Application

We can use the logger class to do application logging in Scala. It is present inside the com.typesafe.scalalogging package, and it also internally wraps the Simple Logging Facade for Java (SLF4J) logger.

We’ll see an example for logging using one of the logging frameworks, log4j. But to include it in our application, first, we have to perform the following steps.

Now, we can use it in our code below.

import org.apache.log4j.Logger

object workspace {
    val logger = Logger.getLogger(this.getClass.getName)
    def main(args: Array[String]): Unit = {
        logger.info("We are logging in Scala")
    }
}

Output:

Logger: We are logging in Scala

When the above program is executed, the log file log.out is created in the D:/hero specified in the Log4j.properties folder.

Levels of Logging in Scala

In Scala, we have three levels of logging: debug, info, and error. We also have the trace, but it is just a detailed debugging version.

Info Logging in Scala

This gives information to the user about the activity or events the application has performed. Here we can put logs like application started, database connection established, finished execution, etc.

Error Logging in Scala

This level tells us that there is some error or problem in our application. It could be anything like service not running, failed to establish a database connection, or some other kind of failure.

Debug Logging in Scala

This level helps in performing diagnosis regarding the application. Once we have found an error in the application, we have to debug, meaning find out where or what is causing it and fix it as soon as possible.

Trace Logging in Scala

A descriptive or detailed version of the debug level.