做题的时候遇到了sort，想试试Java 8的新语法。于是有了一些研究：

Reference

  1. Very confused by Java 8 Comparator type inference

  2. access field by lambda. intervals is a list of interval. intervals.sort(Comparator.comparingInt((Interval i) -> i.start));

Comparator.comparing((Person p)->p.firstName) .thenComparing(p->p.lastName) .thenComparingInt(p->p.age);

Comparator.comparing(Person::getFirstName) .thenComparing(Person::getLastName) .thenComparingInt(Person::getAge);

@Override public int compareTo(Person o){ return Comparator.comparing(Person::getFirstName) .thenComparing(Person::getLastName) .thenComparingInt(Person::getAge) .compare(this, o); }

reference:

https://dzone.com/articles/java-8-comparator-how-to-sort-a-list