CODEWITHSUNDEEP
javagenerics
Amby
Amby

Reputation: 467

Difference between List<Integer> and List<? super Integer>

What is the difference between List<Integer> and List<? super Integer> .

Which one is a good practice or When we should use what ?

Upvotes: 5

Views: 3769

Answers (3)

newacct
newacct

Reputation: 122439

The most obvious difference is that you can get elements out of List<Integer> as type Integer, but when you get elements out of List<? super Integer>, you can only get type Object.

Upvotes: 1

Buhake Sindi
Buhake Sindi

Reputation: 89169

List<Integer> is a List that is bounded to a type Integer. This means that it can receive and produce Integer.

List<? super Integer> is a unbounded List that accepts any value that is a Integer or a superclass of Integer.

The 2nd option is best used on the PECS Principle (PECS stands for Producer Extends, Consumer super). This is useful if you want to add items based on a type T irrespective of it's actual type.

For more information, see a related post here.

Upvotes: 5

Makky
Makky

Reputation: 17463

List<Integer> is the best option here.

List<? super AbstractObject> would be better option if you are dealing with polymorphism.

Upvotes: 0

Related Questions