When assigning an int array to another int array variable, if we perform Arrays.sort on the new array variable, does it affect the original int array?

Question

Here is the code block I am referring:

public class ExtraCandies
{
    public static void main(String[] args)
    {
        int[] candies = {2,3,5,1,3};

        int temp = 0;
        List<Boolean> isGreatestPossibleList = new ArrayList<>();
        int[] tempArray = candies;

        Arrays.sort(tempArray);

        //Here the debugger shows both tempArray and candies array as sorted.
    }
}

When I debug this code, I get that the tempArray gets sorted just fine. And the tempArray becomes {1,2,3,3,5}. But the debugger now also shows the candies array got sorted. I am confused how can this be? Shouldn't the sort method only sort the tempArray here?

Short answer is Yes. It does affect the "original" array, because you have copied the array *reference* not the array. — Stephen C, Feb 26 '21 at 01:43
I have a dup-closed this as a dup of a question that explains what assigning one array variable to another actually does. What you are seeing is a direct consequence of that. — Stephen C, Feb 26 '21 at 01:50

score 1 · Answer 1 · answered Feb 26 '21 at 01:33

Assigning an array to another array is not actually duplicating it - you are just setting the reference of the original array to the new one. Sorting the array would mean sorting the reference, thus sorting both arrays.

You'll want to use a for loop, or Arrays.copyOf(array, length)

public class ExtraCandies
{
    public static void main(String[] args)
    {
        int[] candies = {2,3,5,1,3};

        int temp = 0;
        List<Boolean> isGreatestPossibleList = new ArrayList<>();
        int[] tempArray = Arrays.copyOf(candies, candies.length);

        Arrays.sort(tempArray);

        //Here the debugger shows both tempArray and candies array as sorted.
    }
}

When assigning an int array to another int array variable, if we perform Arrays.sort on the new array variable, does it affect the original int array?

1 Answers1