FirstClassCollections.java

enum COLOR {
    WHITE, BLACK
}

enum PIECE {
    NONE, BISHOP, KING // etc.
}

class Cell {
    private COLOR color; // Enum, white or black
    private PIECE piece;

    public Cell(COLOR color, PIECE piece) {
        this.color = color;
        this.piece = piece;
    }

    public void setPiece(PIECE piece) {
        // validations
        this.piece = piece;
    }

    // much more functionality
}

class ChessBoard {
    private List<Cell> cells;
    private String theme;

    public ChessBoard(List<Cell> cells, String theme) {
        this.cells = cells;
        this.theme = theme;
    }
    // much more functionality
}