Now, let’s introduce the sort() method in the List interface. Only classes i.e.AbstractList and MyList can actually implement this method.
Obviously, it’s impossible to enforce the same sort() implementation in both classes, even though it makes sense. Direct implementations of List have to duplicate (yuck!) the sort() of AbstractList.
In order to remove the duplication and DRY the design, Java API designers have moved the sort() method out of List to an unrelated class with only staticmethods.