sorting - Java 8: sort list of objects by attribute without custom comparator

Question

What is the cleanest short way to get this done ?

class AnObject{
    Long  attr;
}

List<AnObject> list; 

I know it can be done with custom comparator for AnObject. Isn't there something ready out of the box for such case?

Kind of like this:

Collections.sort(list, X.attr);

Answer 1

Assuming you actually have a List<AnObject>, all you need is

list.sort(Comparator.comparing(a -> a.attr));

If you make you code clean by not using public fields, but accessor methods, it becomes even cleaner:

list.sort(Comparator.comparing(AnObject::getAttr));