Reverse an array with static method VS static void?

Question

I have found several threads how to reverse an array. However, I don't follow why can't use the same code for both a static method and a void method.

Can someone explain the difference in the following examples?

For a static method we can write:

public static double[] reverse (double[] a) 
{
        int n = a.length;
        for (int i = 0; i < n/2; i++) 
        {
            double temp = a[i];
            a[i] = a[n-(i+1)];
            a[n-(i+1)] = temp;
        }
        return a;
}

But for a static void we have:

public static void reverse (double[] a) 
{
    for (int i = 0, j = a.length-1; i < j; i++, j--)
    {
        double temp = a[i];
        a[i] = a[j];
        a[j] = temp;
    }
}

In the first case you are returning an array itself, in second case you just modify an existing array and return nothing — Akceptor, Feb 05 '19 at 14:40
They are just two different ways of reversing an array, and the non-void method returns the array. — Steve Smith, Feb 05 '19 at 14:41
Possible duplicate of [Void and return in Java - when to use](https://stackoverflow.com/questions/17527555/void-and-return-in-java-when-to-use) — Akceptor, Feb 05 '19 at 14:57

score 1 · Answer 1 · answered Feb 05 '19 at 14:57

First of all both methods in your case are static. They just have different return type

For the static void reverse (double[] a) case you do like this:

double[] arr = //some array
reverse(arr); //at this point arr is reversed so that you can use it 
reversedArr = arr; //or assign to different variable

Actually its ok if you have to reverse some internal array but I still don't like it because not too obvious the array is changed. I don't think its good to have such a method public...

static double[] reverse (double[] a) is good to be part of some utility class i.e.

double[] arr = //some array
reversedArr = ArrayUtils.reverse(arr); // now you can reuse method and you actually see that you changed the array

But you should modify a method not to change initial array, because you may run into trouble (calling an utility method should not modify the initial value)

Reverse an array with static method VS static void?

1 Answers1