Finding the median value from a List of objects using Java 8

Question

I have two classes that are structured like this:

public class Company {
     private List person;
     ...
     public List getP         


        

Answer 1

You may use

List list = company.getPerson();
DoubleStream sortedAges = list.stream().mapToDouble(Person::getAge).sorted();
double median = list.size()%2 == 0?
    sortedAges.skip(list.size()/2-1).limit(2).average().getAsDouble():        
    sortedAges.skip(list.size()/2).findFirst().getAsDouble();

The advantage of this approach is that it doesn’t modify the list and hence also doesn’t rely on its mutability. However, it’s not necessarily the simplest solution.

If you have the option of modifying the list, you can use

List list = company.getPerson();
list.sort(Comparator.comparingDouble(Person::getAge));
double median = list.get(list.size()/2).getAge();
if(list.size()%2 == 0) median = (median + list.get(list.size()/2-1).getAge()) / 2;

instead.