1import java.util.ArrayList;
2import java.util.List;
3 
4public class Main {
5    public static double sumList(List<? extends Number> list) {
6        double total = 0;
7        for (Number n : list) {
8            total += n.doubleValue();
9        }
10        return total;
11    }
12 
13    public static void main(String[] args) {
14        List<Integer> ints = new ArrayList<>();
15        ints.add(1);
16        ints.add(2);
17        ints.add(3);
18 
19        List<Double> doubles = new ArrayList<>();
20        doubles.add(1.5);
21        doubles.add(2.5);
22 
23        System.out.println(sumList(ints));
24        System.out.println(sumList(doubles));
25    }
26}