JAVA wildcard tutorial

https://www.geeksforgeeks.org/wildcards-in-java/

//Java program to demonstrate Upper Bounded Wildcards

import java.util.Arrays;

import java.util.*;

 

class Main

{

    public static void main(String[] args)

    {

         

        //Upper Bounded Integer List

        List<Integer> list1= Arrays.asList(4,5,6,7);

         

        //printing the sum of elements in list

        System.out.println("Total sum is:"+sum(list1));

 

       // Double list

        List<Double> list2=Arrays.asList(4.1,5.1,6.1);

         

        //printing the sum of elements in list

       System.out.print("Total sum is:"+sum(list2));

    }

 

    private static double sum(List<? extends Number> list) 

    {

        double sum=0.0;

        for (Number i: list)

        {

            sum+=i.doubleValue();

        }

 

        return sum;

    }

}