The Java Language Specification, Third Edition

6.6 Access Control NAMES
138
DISCUSSION
Like expression names, method names may be qualified by type names, but not by types in
general. The implications are similar to those for expression names as discussed in
§6.5.6.2.
6.6 Access Control
The Java programming language provides mechanisms for access control, to prevent
the users of a package or class from depending on unnecessary details of the
implementation of that package or class. If access is permitted, then the accessed
entity is said to be accessible.
Note that accessibility is a static property that can be determined at compile
time; it depends only on types and declaration modifiers. Qualified names are a
means of access to members of packages and reference types; related means of
access include field access expressions (§15.11) and method invocation expressions
(§15.12). All three are syntactically similar in that a “.” token appears, preceded
by some indication of a package, type, or expression having a type and
followed by an Identifier that names a member of the package or type. These are
collectively known as constructs for qualified access.
Access control applies to qualified access and to the invocation of constructors
by class instance creation expressions (§15.9) and explicit constructor invocations
(§8.8.7.1). Accessibility also effects inheritance of class members (§8.2),
including hiding and method overriding (§8.4.8.1).
DRAFT
6.6.1 Determining Accessibility
• A package is always accessible.
• If a class or interface type is declared public, then it may be accessed by any
code, provided that the compilation unit (§7.3) in which it is declared is
observable. If a top level class or interface type is not declared public, then it
may be accessed only from within the package in which it is declared.
• An array type is accessible if and only if its element type is accessible.