These arrays are used to get row and column numbers of 8 neighboursof a given cell
static int rowNum [ ] = { - 1 , - 1 , - 1 , 0 , 0 , 1 , 1 , 1 } ; static int colNum [ ] = { - 1 , 0 , 1 , - 1 , 1 , - 1 , 0 , 1 } ;