What's the output of the following code?

int[][] a = new int[][];

int i, j;
for (i = 0; i < a.length; i++) {
    System.out.print("{ ");
    for (j = 0; j < a[i].length - 1; j++) {
        System.out.print(a[i][j] + ", ");
    }
    System.out.println(a[i][j] + " }");
}