why can't java have types as arguments?

why can't java have types as arguments ?

e.g. can't have Vector of reals where 开发者_如何学Pythoncompiler checks type.

(example taken from http://www.ics.uci.edu/~kibler/javacourse/java.html)

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I think that might be outdated, as now you can do:

Vector<Real> vec = new Vector<Real>();

and the compiler will signal an error if you try to :

vec.add(new Animal());

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Because that page is 12 years old and not very well written besides. Java actually does have generics.

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Use a collection with generics support, such as Vector<Double> instead of its non generic counterpart.

Nowadyas Java does support "types as parameters", or genericity. Read more on that here. Your link is referring to ancient Java versions.