Why use SLF4J over Log4J for logging in Java? Example

Every Java programmers know that logging is critical for any Java application, especially server-side application, and many of them are already familiar with various logging libraries e.g. java.util.logging, Apache log4j, logback, but if you don't know about SLF4J, Simple logging facade for Java,  then it's time to learn and use SLF4J in your project. In this Java article, we will learn why using SLF4J is better than using log4j or java.util.logging. It’s been a long time, since I wrote 10 logging tips for Java programmer,I don’t remember anything I have writing about logging.

How to fix java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory

java.lang.ClassNotFoundException: org.apache.commons.logging.LogFactory or "Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/commons/logging/LogFactory" exception comes when you don't apache commons-logging-1.1.1.jar in your Classpath. I have faced this exception many times while using open-source frameworks like Struts, Spring, and Displaytag which uses a commons-logging framework for logging. commons-logging is not an actual java logging framework but provides a wrapper so that you can use log4j, java logging, or any other Java logging framework.

Why use Log4j logging vs System.out.println in Java? Answer

Printing messages to the console is an integral part of the development, testing, and debugging of a Java program. If you are working on a Server-side application, where you can not see what's going on inside the server, your only visibility tool is a log file; without logs, you can not do any debugging or see what's going on inside your application. Though, Java has a pretty handy System.out.println() method to print something on the console, which can also be routed to log file but not sufficient for a real-world Java application.