Looping Through 2D Array?

looping through 2d arrays.

This code works when printing '*' to show the number of elements in a 2d array:

static int [][] gameboard = new int[3][7];

for (int i = 0; i < gameboard.length ; i++) {

for (int j = 0; j < gameboard[0].length ; j++) {

System.out.print("*");

Thread.sleep(1000);

but then this does not:

static int [][] gameboard = new int[3][7];

for (int i = 0; i < gameboard.length ; i++) {

for (int j = 0; j < gameboard[i].length ; j++) {

System.out.print("*");

Thread.sleep(1000);

The difference is on the third line where i did gameboard[i] instead of gameboard[0]. I get a runtime error on the second one.