Converting List> to Array>

Question

I am writing a method which converts Integer data type from a List of lists, to a primitive type \"int\" of \"array of array\".

Question

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Answer 1

This

tempArray[i][j] = ll.get(j);

should be something like

tempArray[i][j] = ll.get(i).get(j);

However, you have a few other bugs (you need to declare the arrays); you can also shorten the initialization routines. Something like,

static int[][] convert(int[] set) {
    List> ll = new ArrayList<>();
    ll.add(Arrays.asList(1,2));
    ll.add(Arrays.asList(2));
    ll.add(Arrays.asList(2,3));

    System.out.println(ll + " " + ll.size());

    int[][] tempArray = new int[ll.size()][];
    for (int i = 0; i < ll.size(); i++) {
        tempArray[i] = new int[ll.get(i).size()];
        for (int j = 0; j < tempArray[i].length; j++) {
            tempArray[i][j] = ll.get(i).get(j);
        }
    }
    return tempArray;
}