java - 参数多态性和子类型多态性之间的概念区别？

Question

我曾尝试通读维基百科，但它对多态性(特别是与 Java 相关)的主题非常详尽。我的理解是子类型多态性与子类型相关，而参数多态性与跨不同对象/类泛化的方法相关？我错过了什么？

Answer 1

As the article says ,

Parametric polymorphism allows a function or a data type to be written generically, so that it can handle values identically without depending on their type ... Parametric polymorphism is also available in several object-oriented languages, where it often goes under the name "generics" (for example, Java) or "templates" (C++ and D)

所以这意味着(作为示例)您可以创建一个函数，该函数接受 somethings 的列表，并且无论那些 somethings 是什么，该函数都可以工作.想想一个返回集合中元素数量的方法。您可以传入任何类型元素的列表，它会返回一个答案。您不必为传入的每种列表重写函数。

Some languages employ the idea of subtyping to restrict the range of types that can be used in a particular case of polymorphism. In these languages, subtype polymorphism (sometimes referred to as inclusion polymorphism or dynamic polymorphism[citation needed]) allows a function to be written to take an object of a certain type T, but also work correctly if passed an object that belongs to a type S that is a subtype of T

换句话说，您可以拥有一个将 Animal 作为参数的方法，但您也可以将 Cat 或 Dog 传入其中，因为 Cats 和 Dog 是动物。