It is extremely important to follow coding conventions that are followed industry-wide, especially for Java. Understanding someone else's code or even your own becomes so much easier! It's like English grammar (start proper nouns with a capital letter, the first letter of a sentence should be capital, etc).
When people don't follow conventions especially for naming, I get very very annoyed. You don't want to mess with me then.
Here're some good documentation that I found on the topic: