Java does not enforce a particular code quality language-wise and therefor programmers should follow certain guidelines when writing code. As all guidelines, they might be violated for a good reason.

• Java code conventions
• Google Java code style

• All public class fields must be final static:

  public final static int MY_CONST = 3;

• Class members have to be named uppercase with underscore between words: MAX_INTEGER

• All fields must be private and only accessible through getters and setters.
• All fields must be final unless functionality requires mutability.

• Constructors must not call any method unless it is private and in turn does not call any non-private method.
• Fields assigned in the constructor must be private final