arraylist of a three-dimensional integer vector

Question

I have this three-dimensional array named bands. I need to do 4 copies of it, so I can work in parallel with all of them.

int bands[][][] = new int[param][][];

I need the array to keep being a three dimensional array, as it is the input for some methods that needs an int [][][]

How could I do such copies? I was thinking about using an arrayList like this:

List<Integer[][][]> bandsList = new ArrayList<Integer[][][]>();

bandsList.add(bands);

but I get this error on the last line: The method add(Integer[][][]) in the type List<Integer[][][]> is not applicable for the arguments (int[][][])

so what should I do??

Use List<int[][][]> instead. But what you are doing is making me crazy. Why you actually want to do something like this? Is there any specific use case which forces you? — Rohit Jain
– Rohit Jain, Commented Feb 17, 2013 at 14:39
Storing an array in a list won't make any copy of the array. You'll just have 4 references to the same array. — JB Nizet
– JB Nizet, Commented Feb 17, 2013 at 14:41
Not the best idea to copy something in order to access it concurrently..its difficult to modify all the copy and merge them. — Shivam
– Shivam, Commented Feb 17, 2013 at 14:42
first... I didn't know List<Integer[][][]> was different from List<int[][][]>, so thanks... you can assume I am pretty lost So I had in mind that if I had such list I could then use: for (int i=0; i<4;i++){ method(Listbands.get(i)) } — strv7
– strv7, Commented Feb 17, 2013 at 14:52

Bernhard Barker · Accepted Answer · 2013-02-17 14:58:07Z

The errors is because int[][][] is not the same as Integer[][][].

int[][][] is an 3D array of primitive int.

Integer[][][] is an 3D array of object Integer, which is the wrapper class of int.

Well, technically a 3D array is an array of pointers to a 2D array, which is an array of pointers to a 1D array which is an array of primitives or pointers to objects.

Use List<int[][][]> bandsList = new ArrayList<int[][][]>(); instead.

Also note that

bandsList.add(bands);
bandsList.add(bands);

will simply add 2 pointers to the same array, changing one will also change the other.

You'll need to manually copy them:

int[][][] getCopy(int[][][] bands)
{
  int[][][] newBands = new int[bands.length][][];
  for (int i = 0; i < bands.length; i++)
  {
    newBands[i] = new int[bands[i].length];
    for (int j = 0; j < bands[i].length; j++)
    {
      newBands[i][j] = new int[bands[i][j].length];
      System.arraycopy(bands, 0, newBands, 0, bands[i][j].length))
    }
  }
  return newBands;
}

// to add
bandsList.add(getCopy(bands));

Giudark · Accepted Answer · 2013-02-17 15:06:42Z

0

in this way you aren't doing a copy of the array, you have to do this 4 times:

    int cloneList[][][] = new int[param][..][..];
    for(int i = 0; i<bands.length; i++) {
       int arr1[][] = bands[i];
       for(int j = 0; j<arr1.length; j++) {
           int arr2[] = arr1[j];
           for(int k = 0; k<arr2.length; k++) {
               int x = arr2[k];
               cloneList[i][j][k] = x;
           }
       }
    }

answered Feb 17, 2013 at 15:06

Giudark

791 silver badge7 bronze badges

Collectives™ on Stack Overflow

arraylist of a three-dimensional integer vector

2 Answers 2

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related