Static methods and type parameters in Java Language Specification

Question

I read in the JLS 7 the following sentence.

It is a compile-time error to use the name of a type parameter of any surrounding declaration in the header or body of a class method.

Please explain its meaning.

Add the link of JLS here. Otherwise, it's hard to know the context — Abimaran Kugathasan
– Abimaran Kugathasan, Commented Apr 12, 2014 at 15:31
I have a copy available at the office which I cannot share. This sentence appears in the section where static modifier for a method is explained. — Pankaj Dwivedi
– Pankaj Dwivedi, Commented Apr 12, 2014 at 15:36
docs.oracle.com/javase/specs/jls/se7/html/jls-8.html point 8.4.3.2 — TomasZ.
– TomasZ., Commented Apr 12, 2014 at 15:39

Paul Draper · Accepted Answer · 2014-04-12 16:05:37Z

5

It means you can't do

class Test<T> {
    static void f(T a) {
    }
}

You have to do

class Test<T> {
    static <T> void f(T a) {
    }
}

The generic types of a static method are independent of generic types of the class or other methods.

So you can even do something like

class Test {
    static <A, B, C> void f(A a, B b, C c) {
    }
}

answered Apr 12, 2014 at 15:37

Paul Draper

84.2k53 gold badges216 silver badges303 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Paul, Thanks for the clarification. Does this mean I can use any other generic type in a static method than the one used by the class?