This is a very common problem, it occurs when log4j.properties not found in classpath.
Create a file called log4j.properties. Place it in the root folder where your java classes are found. When log4j initializes, it will look for a file named EXACTLY log4j.properties (if you are using a properties file).
Another alternate way is to put the path to the log4j.properties file in your classpath.
Hope this will help you 🙂