Çàäà÷à . 18

   public class Position
    {
        /** row and col are both >= 0 except in the default
        * constructor where they are initialized to -1.
        */
        private int row, col;
        public Position() //constructor
        {
            row = -1;
            col = -1;
        }
        public Position(int r, int c) //constructor
        {
            row = r;
            col = c;
        }
        /** @return row of Position */
        public int getRow()
        { return row; }
        /** @return column of Position */
        public int getCol()
        { return col; }
        /** @return Position north of (up from) this position */
        public Position north()
        { return new Position(row - 1, col); }
        //Similar methods south, east, and west
          ...
/** Compares this Position to another Position object.
* @param p a Position object
* @return -1 (less than), 0 (equals), or 1 (greater than)
*/
    public int compareTo(Position p)
        {
            if (this.getRow() < p.getRow() || this.getRow() == p.getRow()
            && this.getCol() < p.getCol())
                return -1;
            if (this.getRow() > p.getRow() || this.getRow() == p.getRow()
            && this.getCol() > p.getCol())
                return 1;
            return 0; //row and col both equal
        }
        /** @return string form of Position */
        public String toString()
        { return "(" + row + "," + col + ")"; }
    }
    public class PositionTest
    {
        public static void main(String[] args)
        {
            Position p1 = new Position(2, 3);
            Position p2 = new Position(4, 1);
            Position p3 = new Position(2, 3);
           //tests to compare positions
            ...
        }
    }