New to Java

I'm trying to make a seperate java class(there is another main that calls this using SWING interface) that makes mark on the board.

It's supposed to do the following

Method makeMark returns:

a null if the cell indicated by row and column has already been marked
an X if it is X's turn (X gets to go first)
a Y if it is Y's turn

Thus makeMark will have to keep of marks made previously and return the appropriate string
for the requested cell.

and here is what I got so far, but only getting empty clicks as a respond. Any help will be appreciated. thanks.

import javax.swing.JButton;

public class TicTacToeGame {

public String makeMark(int row, int column){
String player = "X";
String [][] Enum = new String [3][3];


for (row=0; row<=2; row++){
for (column=0; column<=2; column++)
{
if (Enum[row][column] == "")
{
if (player == "X"){
Enum[row][column] = "X";
player = "Y";
return "X";
}

if (player == "Y"){
Enum[row][column] = "O";
player = "X";
return "Y";
}
}
else
return null;
}
}

return player;
}

}