February 2013
Intermediate to advanced
672 pages
16h 2m
English
book
The Java® Language Specification, Java SE 7 Edition, Fourth Edition
by James Gosling, Bill Joy, Guy Steele, Gilad Bracha, Alex Buckley
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4.10. Subtyping
The subtype and supertype relations are binary relations on types.
The supertypes of a type are obtained by reflexive and transitive closure over the direct supertype relation, written S >1 T, which is defined by rules given later in this section. We write S :> T to indicate that the supertype relation holds between S and T.
S is a proper supertype of T, written S > T, if S :> T and S ≠ T.
The subtypes of a type T are all types U such that T is a supertype of U, and the null type. We write T <: S to indicate that that the subtype relation holds between types T and S.
T is a proper subtype of S, written T < S, if T <: S and S ≠ T.
T is a direct subtype of S, written T <1 S, if S >1 T.
Subtyping does not extend through parameterized ...
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