Java: How to represent 1d string/int array into 2d int array?

Question

// Java: How to represent 1d string/int array into 2d int array? I would really appreciate your help.

package intro;
public class ArrayTest{

    public static void main(String[] args) {

        int arr[][]= new int[4][4];   
        int month_days [] = {31,28,31,30,31,30,31,31,30,31,30,31,13,14,15,16};

        int size =4;
        //System.out.println(size);
        for (int i = 0, k = 0; i < size; i++, k++) {
            for(int j=0; j <size; j++){
                arr[i][j]= month_days[k++];

                //System.out.println(month_days[k++] + " ");
                System.out.print(arr[i][j] + " ");
            }

            System.out.println();
        }
    }
}

Answer 1

You increment k too often. You increment it in the for-loop and here: month_days[k++].
Remove the increment from the for-loop:

for (int i = 0, k = 0; i < size; i++)

Answer 2

Change arr[i][j] = month_days[k++]; to arr[i][j] = month_days[k];

Every instance of k++ is incrementing k by 1. Currently, you're incrementing it twice per iteration of your for loop, so after the 8th iteration, it's looking to put the 17th element of month_days[] into arr[][], but month_days[] doesn't have that many elements.

Answer 3

You are already incrementing your 'k' variable in this line: month_days[k++];

You don't need to increment it in this line as well: for (int i = 0, k = 0; i < size; i++, k++) {

Basically, you are throwing away a 'k' value each time your loop runs, which makes you run out of values before you can fill your array.