Hello!

I need help with these following exercises:

Setup

Create a Java class called ListProcessor

ListProcessor should contain all of the following methods specified in the below exercises.

Exercise 3: Summing Lists Iteratively

Implement methods with the following headers:

public int sumIterative(int[] numbers) 

and

public int sumIterative(List numbers) 

These methods should return the sum of a list of numbers using iteration.

Special cases:

The sum of an empty list should be 0.

requirement: Again, the argument should not be mutated.

Exercise 4: Summing Lists Recursively

Implement methods with the following headers:

public int sumRecursive(int[] numbers) 

and

public int sumRecursive(List numbers) 

These methods should do exactly the same thing as the ones in Exercise 3, but using recursion instead of iteration. There are several strategies that you may use here. You may also create private helper methods if required. Finally, there are some useful methods in java.util.Arrays and java.util.ArrayList that may help depending on your strategy.

requirement: Again, the argument should not be mutated.

What does it mean that "the argument should not be mutated"? I really need help with this cause I don't understand what to do :( and how to solve these.

Thank you for helping!