Java Generics: Difference between revisions
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O'Reilly Java Generics and Collections. | O'Reilly Java Generics and Collections. | ||
=Organizatorium= | |||
* '''Covariance''' Let T and S be two types (class or function types), such that S is a subtype of T. If method m of T is overridden in S, then the corresponding types from the m's signature can either preserve the relationship between T and S (the type used in S is a subtype of the corresponding type in T), reverse the relationship (the type used in S is a super type of the type used in T), or neither preserve nor reverse this relationship. If they preserve the relationship to T and S, we say they are covariant, if they reverse the relationship of T and S, we say they are contravariant. | |||
Revision as of 02:16, 14 June 2018
Internal
TODO
O'Reilly Java Generics and Collections.
Organizatorium
- Covariance Let T and S be two types (class or function types), such that S is a subtype of T. If method m of T is overridden in S, then the corresponding types from the m's signature can either preserve the relationship between T and S (the type used in S is a subtype of the corresponding type in T), reverse the relationship (the type used in S is a super type of the type used in T), or neither preserve nor reverse this relationship. If they preserve the relationship to T and S, we say they are covariant, if they reverse the relationship of T and S, we say they are contravariant.