The Java Language Specification, Third Edition

CHAPTER8
Classes
Origins: A Short Etymological Dictionary of Modern English
CLASS declarations define new reference types and describe how they are
implemented (§8.1).
A nested class is any class whose declaration occurs within the body of
another class or interface. A top level class is a class that is not a nested class.
This chapter discusses the common semantics of all classes—top level (§7.6)
and nested (including member classes (§8.5, §9.5), local classes (§14.3) and anonymous
classes (§15.9.5)). Details that are specific to particular kinds of classes are
discussed in the sections dedicated to these constructs.
A named class may be declared abstract (§8.1.1.1) and must be declared
abstract if it is incompletely implemented; such a class cannot be instantiated,
but can be extended by subclasses. A class may be declared final (§8.1.1.2), in
which case it cannot have subclasses. If a class is declared public, then it can be
referred to from other packages. Each class except Object is an extension of (that
is, a subclass of) a single existing class (§8.1.4) and may implement interfaces
(§8.1.5). Classes may be generic, that is, they may declare type variables (§4.4)
whose bindings may differ among different instances of the class.
Classes may be decorated with annotations (§9.7) just like any other kind of
declaration.
The body of a class declares members (fields and methods and nested classes
and interfaces), instance and static initializers, and constructors (§8.1.6). The
scope (§6.3) of a member (§8.2) is the entire body of the declaration of the class to
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