javaType errorMedium

List size issues when adding elements in Java

Time: 0:00

BugFind the bug and fix the code

What it should do

Add an element to a list and return the updated list. Example: f([1, 2], 3) -> [1, 2, 3]

What happens instead

Exception in thread "main" java.lang.UnsupportedOperationException

import java.util.List;

public class Main {
    public static List<Integer> addElementToList(List<Integer> list, int element) {
        list.add(element);
        return list;
    }

    public static void main(String[] args) {
        List<Integer> list = Arrays.asList(1, 2);
        System.out.println(addElementToList(list, 3));
    }
}

Test a custom input to verify an edge case (e.g. empty lists, negative numbers, duplicates).

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This bug belongs to the type errors pattern

Totals that concatenate, sorts that put 10 before 9, comparisons that refuse to run.

Learn the type errors pattern Step through your own code

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import java.util.List; public class Main { public static List<Integer> addElementToList(List<Integer> list, int element) { list.add(element); return list; } public static void main(String[] args) { List<Integer> list = Arrays.asList(1, 2); System.out.println(addElementToList(list, 3)); } }

List size issues when adding elements in Java

What it should do

What happens instead

More type errors to practise

List size issues when adding elements in Java

What it should do

What happens instead

More type errors to practise