Practice›Java Fundamentals›Module 9. Generics›9.3 Wildcards

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9.3 Wildcards — fill a list with a range

Total: 0 / 3 pts

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Task

Fill in addRange so that it adds the whole numbers 1 through n to the given list, in order. It returns nothing.

Thanks to ? super Integer the same method fills a List<Number> or a List<Object>. The program prints [1, 2, 3] and then [].

Your solution

import java.util.ArrayList;
import java.util.List;

public class Main {

    public static void addRange(List<? super Integer> list, int n) {
        // add 1 through n to the list

    }

    public static void main(String[] args) {
        List<Number> nums = new ArrayList<Number>();
        addRange(nums, 3);
        System.out.println(nums);
        List<Object> objs = new ArrayList<Object>();
        addRange(objs, 0);
        System.out.println(objs);
    }
}

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