<T extends Object & E> vs <T extends E> [duplicate]

Question

The signature of java.util.Collections.max looks like this:

public static <T extends Object & Comparable<? super T>> T max(Collection collection);

From what I understand, it basically means that T must be both a java.lang.Object and a java.lang.Comparable<? super T>>,

However, since every java.lang.Comparable is also an java.lang.Object, what is the difference between the signature above and this below? :

public static <T extends Comparable<? super T>> T max(Collection collection);

nobeh · Accepted Answer · 2012-04-26 18:42:46Z

33

To preserve binary compatibility: It's completely described here. The second signature actually changes the return type of the method to Comparable and it loses the generality of returning an Object. The original signature preserves both.

answered Apr 26, 2012 at 18:42

nobeh

10.1k10 gold badges53 silver badges68 bronze badges

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

3 Comments

Pacerier Over a year ago

Thanks for the link =) Btw are you aware of any tools to examine the erased signatures after compilation?

nobeh Over a year ago

Not that I know of, but maybe this can give some clues on the topic. I also suggest reading the section on "Type Erasure" at Angelika Langer's Generics FAQ.

Stuart Marks Over a year ago

@Pacerier, yes, use "javap -s".

Collectives™ on Stack Overflow

<T extends Object & E> vs <T extends E> [duplicate]

1 Answer 1

3 Comments

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

3 Comments

Linked

Related