gistfile1.java

class Board {
    final int boardSize = 2;
    Square[][] pos;

    /* create empty board */
    public Board() {
        pos = new Square[boardSize][boardSize];
        for (int row = 0; row < boardSize; row++)
            for (int col = 0; col < boardSize; col++) {
                pos[row][col] = new Square(row, col);
            }
    }

    /** A copy constructor */
    public Board(Board other) {
        pos = new Square[boardSize][boardSize];
        for (int row = 0; row < boardSize; row++)
            for (int col = 0; col < boardSize; col++) {
                // we need to provide a reference to the new outter class - ourself: this
                this.pos[row][col] = other.pos[row][col].createAClone(this);
            }
    }

    class Square {
        int row;
        int col;

        public Square(int r, int c) {
            row = r;
            col = c;
        }

        /** A clone method of this inner class with an argument of enclosing class */ 
        public Square createAClone(Board referenceToEnclosingClass) {
            return referenceToEnclosingClass.new Square(row, col);
        }

        public int gameHash() {
            return Board.this.hashCode();
        }
    }
}