CellVector.java

public class CellVector {

    private static final CellVector [] neighbourShifts = {
            new CellVector (-1,  0),
            new CellVector ( 0, -1),
            new CellVector ( 1,  0),
            new CellVector ( 0,  1),
            new CellVector (-1, -1),
            new CellVector ( 1, -1),
            new CellVector (-1,  1),
            new CellVector ( 1,  1),
    };

    private static final char [] moveLetter = {'l', 'u', 'r', 'd'};

    private static final int [] rearIndex = {2, 3, 0, 1, 7, 6, 5, 4};

    private int x, y;

    public CellVector (int ax, int ay) {
        x = ax;
        y = ay;
    }

    public CellVector (int [] arg) {
        x = arg [0];
        y = arg [1];
    }

    public CellVector sumWith (CellVector arg) {
        return new CellVector (x + arg .x, y + arg .y);
    }

    public CellVector neighbour (int index) {
        return sumWith (neighbourShifts [index]);
    }

    public CellVector rearNeighbour (int index) {
        return sumWith (neighbourShifts [rearIndex [index]]);
    }

    public char moveLetter (int index) {
        return moveLetter[index];
    }

    public int getCell (int [] [] array) {
        return array [y] [x];
    }

    public void setCell (int [] [] array, int value) {
        array [y] [x] = value;
    }

    public short getCell (short [] [] array) {
        return array [y] [x];
    }

    public void setCell (short [] [] array, short value) {
        array [y] [x] = value;
    }

    public int getX () {
        return x;
    }

    public int getY () {
        return y;
    }

    public boolean outOfBorder (CellVector border) {
        if (0 > x || 0 > y) {
            return true;
        }
        if (border .x <= x || border .y <= y) {
            return true;
        }
        return false;
    }

    public String toString () {
        return "(" + x + ", " + y + ")";
    }
}