Deep copy/clone method for arrays

[Ruben Soto]

Is there a deep copy/clone method for arrays? What I mean is a method which will clone a multidimensional array so that each array element is a reference to a new array object, and not another reference to a shared array. As far as I can tell this is how the Arrays.copyOf() and clone() methods work:

/*
Output is:
true
true
*/
import java.util.*;

public class ArraysCopyOf {
   public static void main(String[] args) {
      int[][] i2a = {{1, 2}, {3, 4}};
      int[][] i2b = Arrays.copyOf(i2a, 2);
      System.out.println(Arrays.equals(i2a[0], i2b[0]));
      System.out.println(i2a[0] == i2b[0]);
   }
}

Thanks!

[reji singh]

Hi Ruben,

I believe there is none for deep cloning of multi-dimensional arrays at the moment.

It might be due to the dimension of arrays that will limit this functionality to be put in a single method.



For 2D , you can loop through each row and cloning them one-by-one .

Thanks

[Ruben Soto]

Thanks for your answer, Reji. I think there would be ways to implement a method to work with any multidimensional array. You just need to iterate over each element, check whether it's an array, and do this recursively. It might get a little complicated though, since you would need to keep track of every included subarray and the dimensions for each element, so that you can go back and instantiate a new array of whichever dimension is needed. But I don't see any technical limitations.

I would be extremely surprised if someone hasn't already implemented this. Maybe there is a method which does this somewhere in the API which we are missing.

[Bert Bates]

interesting topic, not on the exam

[Ruben Soto]

Yeah, thanks for pointing that out Bert. Maybe I should have used the Basic (or Intermediate) Java forum.