I think that most developers follow the standards that Sun invented long ago: CamelCase for class and interface names, lowerCamelCase for methods and variables, etc. - see the document
Code Conventions for the Java Programming Language, which is and old document (1999) but which still has some relevance.
A book which is not just about coding standards but also about good Java programming practice is
Effective Java - every Java developer should read this book.
Consider using tools such as
Checkstyle,
PMD and
FindBugs, which will check for style and many common programming problems in Java programs.