How to sort an ArrayList?

Question

I have a List of doubles in java and I want to sort ArrayList in descending order.

Input ArrayList is as below:

List testList = new Arr         


        

Answer 1

For your example, this will do the magic in Java 8

List testList = new ArrayList();
testList.sort(Comparator.naturalOrder());

But if you want to sort by some of the fields of the object you are sorting, you can do it easily by:

testList.sort(Comparator.comparing(ClassName::getFieldName));

or

 testList.sort(Comparator.comparing(ClassName::getFieldName).reversed());

or

 testList.stream().sorted(Comparator.comparing(ClassName::getFieldName).reversed()).collect(Collectors.toList());

Sources: https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html