Java Reference
In-Depth Information
}
}
A compile-time error occurs in the method
delta
here: it cannot access the
protected
members
x
and
y
of its parameter
p
, because while
Point3d
(the class in which the ref-
erences to fields
x
and
y
occur) is a subclass of
Point
(the class in which
x
and
y
are
declared), it is not involved in the implementation of a
Point
(the type of the parameter
p
). The method
delta3d
can access the
protected
members of its parameter
q
, because the
class
Point3d
is a subclass of
Point
and is involved in the implementation of a
Point3d
.
cast would fail, causing an exception, if the class of
p
at run time were not
Point3d
.
A compile-time error also occurs in the method
warp
: it cannot access the
protected
member
z
of its parameter
a
, because while the class
Point
(the class in which the ref-
erence to field
z
occurs) is involved in the implementation of a
Point3d
(the type of the
parameter
a
), it is not a subclass of
Point3d
(the class in which
z
is declared).
6.7. Fully Qualified Names and Canonical Names
Every primitive type, named package, top level class, and top level interface has a
fully
qualified name
:
• The fully qualified name of a primitive type is the keyword for that primitive type,
namely
byte
,
short
,
char
,
int
,
long
,
float
,
double
, or
boolean
.
• The fully qualified name of a named package that is not a subpackage of a named
package is its simple name.
• The fully qualified name of a named package that is a subpackage of another
named package consists of the fully qualified name of the containing package, fol-
lowed by “
.
”, followed by the simple (member) name of the subpackage.
• The fully qualified name of a top level class or top level interface that is declared
in an unnamed package is the simple name of the class or interface.
• The fully qualified name of a top level class or top level interface that is declared
in a named package consists of the fully qualified name of the package, followed
by “
.
”, followed by the simple name of the class or interface.
Each member class, member interface, and array type
may
have a fully qualified name:
• A member class or member interface
M
of another class or interface
C
has a fully
qualified name if and only if
C
has a fully qualified name.
