jose chiramal wrote:In the api for java.util.Collections i came across the following syntax :
public static <T extends Comparable<? super T>> void sort(List<T> list)
What does the above syntax mean ?
This declaration says, that argument to sort() method must be of a type List<T>,
where T could be any type that implements Comparable<? super T> (sort requires compareTo method defined in Comparable to compare elements of list)
Comparable<? super T> means that type ? passed to Comparable could be T or any supertype of T.
Consider this code:
Class B doesn't implement Comparable<B> (and doesn't define it's own compareTo(B b) method).
Class B inherits compareTo(A x) method from class B (we can say that it implements Comparamble<A>).
And sort(List<B>) compiles fine, it is conforming with declaration: public static <B extends Comparable<? super B>> void sort(List<B> list)