Java泛型始终用于集合

Question

I have a question about Java Generics. If I define a class like this:

public Test<String> ...

Does this mean that my class now acts like a collection type for Strings? For example when seeing it like this List I know that it is a List of Strings. Does the <> always mean it's a collection (general meaning, not the actual Collection type)?

thanks,

Answer 1

No. It just means that your type is parameterized with the type String. There are plenty of non-collection generic types. See Callable<T> , Future<T> , Comparator<T> for example.

Answer 2

看看http://docs.oracle.com/javase/tutorial/java/generics/

Answer 3

You should start from the beginning: http://docs.oracle.com/javase/tutorial/java/generics/generics.html

Long story short: generics are a completely different concept from collections. Java collections use generics since they were introduced, but you can still use non-generics versions of them.

Answer 4

No it does not! It only mean that Test is parametrized with the String.

Read oracle tutorial for good understanding of Generics.

Answer 5

No.

To do what you mean you add extends Collection<T> to your class declaration