Question: I find reading coding style guidelines to be the best way to get to know a language and its peculiarities. I've been trying to find a good document for Java, and get some questions answered immediately. 

Firstly, what is the convention for very long lines? Writing in both Java and C/C++ leads me to have a great deal of confusion on this point. 

Secondly, what is the guideline for creating custom exception classes? I typically end up throwing an existing exception rather than creating my own. Is custom exception creation typically enforced?

Answer: 
Take a look at the official [Code Conventions for the Java TM Programming Language](http://www.oracle.com/technetwork/java/codeconv-138413.html).
[JavaRanch Java Programming Style Guide](http://www.javaranch.com/style.jsp)

[Code Conventions for the Java Programming Language](http://www.oracle.com/technetwork/java/codeconv-138413.html)

[Java Programming Style Guidelines](http://geosoft.no/development/javastyle.html)