Question

I want to create a multi-dimensional array from a single dimensional array in java.

my single dimenstional array is like

  int[] grid = {5, 3, 1, 2, 0, 4, 1, 1, 3 };

I want to create a matrix of 3×3 diminsions at runtime as there are 9 elements in this array. Can anyone suggest some good idea for this.
Can anyone suggest me what should I do in below code so that it can give me arraylist of 3 arrays or if someone can suggust me some better idea to perform this correctly. I know there is error in my below code.

         ArrayList<int[]> matrix = new ArrayList<>();
    int[] tempArray = new int[n];
    int j = 0;
    for(int i=0 ; i<=grid.length; i++){         

        if((i+1) / 3 == 0){         
            matrix.add(tempArray);
            j=0;
        }else{          
            tempArray[j] = grid[i];
            j++;
        }
    }   

Thanks

Answer 1

Java does multi-dimensional arrays natively; you don’t need to create your own using arrays in an ArrayList.

Something like this should give you what you want:

int[] grid = {5, 3, 1, 2, 0, 4, 1, 1, 3 };
int [][] matrix = new int[3][3];

for (int x = 0; x < 3; x++) {
  for (int y = 0; y < 3; y++) {
    matrix[x][y] = grid[x + y * 3];
  }   
}