Java Array Index Out of Bound Exception 2

Question

I was trying to do a sorting class of matrices entries and I first put them into an array

 double[][] A ={{0,70,9},{1,3,4}};

    double[] vektori_per_sortim=new double[A.length*A[0].length];

    int k=0;

    for(int i=0; i!=A.length; i++)
    {
        for(int j=0; j!=A[0].length; j++)
        {
            vektori_per_sortim[k]=A[i][j];
            k++;
        }

    }

and then I tried to put them into the matrices again

int r=0;
  while(r!=vektori_per_sortim.length)
{
    for(int i=0; i!=vektori_per_sortim.length/A.length; i++)
     {
       for(int j=0; j!=vektori_per_sortim.length/A[0].length; j++)
       {
          A[i][j]=vektori_per_sortim[r];
          r++; 

        }

      }


}

but I get an error java.lang.ArrayIndexOutOfBoundsException: 2

Can you please help me out with this?

Thank you very much.

Most developers would use a debugger to solve this kind of problem. — pamphlet, May 06 '14 at 16:33
What exactly do you mean by `i!=vektori_per_sortim.length/A.length`? — Russell Zahniser, May 06 '14 at 16:34
Let me guess - Your question was identical to a previous one, so you added a 2 to the title. **That means don't ask it.** — djechlin, May 06 '14 at 16:37
@djechlin No, the 2 is the out of bounds index in the error. — McLovin, May 06 '14 at 16:38
If you can write this much code, then you can obviously debug also. So give a try. — Alok Anand, May 06 '14 at 16:38

that other guy · Accepted Answer · 2014-05-06T16:52:57.310

0

The problem is that you mixed up your dimensions, and tried to copy the 6 element vector into a 3x2 matrix rather than a 2x3 matrix.

You can tell because when you copy the values out of the matrix, i goes from 0 to A.length. When you copy them back in, i goes from 0 to A[0].length (= vektori_per_sortim.length/A.length).

You could switch the i and j conditions, but it would be way cleaner to simply use your first loops and reverse the copy inside them:

k=0;
for(int i=0; i!=A.length; i++)
{
    for(int j=0; j!=A[0].length; j++)
    {
        A[i][j] = vektori_per_sortim[k];
        k++;
    }

}

edited May 06 '14 at 16:52

answered May 06 '14 at 16:41

that other guy

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1

You should probably use `k = 0;` at the beginning, otherwise the old value of k will be used. – McLovin May 06 '14 at 16:43
Thank you very much. That worked well. I had been messing with the lengths a little bit. – Fatos Morina May 07 '14 at 04:34

score 0 · Answer 2 · answered May 06 '14 at 16:41

You may want a different approach to putting the values back into the matrix. I would recommend iterating through the elements in the same way that you did to put them into the array, but copying them the other way this time. Try replacing the second code block with this:

int r = 0;
for(int i=0; i!=A.length; i++)
{
    for(int j=0; j!=A[0].length; j++)
    {
        A[i][j] = vektori_per_sortim[r];
        r++;
    }

}

Java Array Index Out of Bound Exception 2

2 Answers2