My favorite sources for Java coding conventions and guidelines:
- Code Conventions for the Java Programming Language (Sun, now Oracle)
- Java Coding Standard (NASA / Jet Propulsion Laboratory, Caltech)
- Secure Coding Standard for Java (CERT / Oracle)
- Book: Effective Java, 2nd ed. (Josh Bloch, Sun / now Google)
- Book: Clean Code (Robert C. Martin aka “Uncle Bob”)