The Java Language Specification, Third Edition

4.8 Raw Types TYPES, VALUES, AND VARIABLES
58
More precisely, a raw type is define to be either:
• The name of a generic type declaration used without any accompanying
actual type parameters.
• Any non-static type member of a raw type R that is not inherited from a superclass
or superinterface of R.
DISCUSSION
The latter point may not be immediately self evident. Presenting for your consideration,
then, the following example:
class Outer{
T t;
class Inner {
T setOuterT(T t1) {t = t1;return t;}
}
}
The type of the member(s) of Inner depends on the type parameter of Outer. IfOuter is
raw, Inner must be treated as raw as well, as their is no valid binding for T.
This rule applies only to type members that are not inherited. Inherited type members
that depend on type variables will be inherited as raw types as a consequence of the rule
that the supertypes of a raw type are erased, described later in this section.
DISCUSSION
Another implication of the rules above is that a generic inner class of a raw type can itself
only be used as a raw type:
class Outer{
class Inner {
S s;
}
}
it is not possible to access Inner as partially raw type (a "rare" type)
Outer.Inner x = null; // illegal
Double d = x.s;
because Outer itself is raw, so are all its inner classes, including Inner, and so it is
not possible to pass any type parameters to it.
DRAFT