/**
* Private method that prints the current ecosystem grid as a string
*
* @return the string printout
*/
private String printX() {
String s = "";
for (int i = 0; i < 3; i++)
for (int j = 0; j < 3; j++) {
Item x = system.getItemAt(new Cell(i, j));
if (x != null) s += x.getSymbol();
else s += "x";
}
return s;
}
