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 list; 

I know it can be done

Answer 1

Assuming you actually have a List, 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));