编写一个名为Octagon的类，它继承自GeometricObject类并实现Comparable和Cloneable接口。假设八边形八条边的边长都相等。它的面积可以使用下面的公式计算： 面积 = ( 2 + 4 / √ 2 ) × 边长 × 边长 面积=(2+4/√2)×边长×边长面积=(2+4/√2)×边长×边长 画出包括Octagon、GeometricObject、Comparable和Cloneable的UML图。编写一个测试程序，创建一个边长值为5的Octagon对象，然后显示它的面积和周长。使用clone方法创建一个新对象，并使用compareTo方法比较这两个对象。

以下是Octagon、GeometricObject、Comparable和Cloneable的UML图：

--------------------------------
|          GeometricObject     |
--------------------------------
|+color: String                |
|+filled: boolean              |
|+dateCreated: Date            |
|+GeometricObject()             |
|+GeometricObject(color: String, filled: boolean) |
|+getColor(): String           |
|+setColor(color: String): void|
|+isFilled(): boolean          |
|+setFilled(filled: boolean): void |
|+getDateCreated(): Date       |
|+toString(): String           |
|+getArea(): double            |
|+getPerimeter(): double       |
|+compareTo(object: Object): int|
|+clone(): Object              |
--------------------------------
                  ^
                  |
                  |
                  |
--------------------------------
|            Comparable        |
--------------------------------
|+compareTo(object: Object): int|
--------------------------------
                  ^
                  |
                  |
                  |
--------------------------------
|            Cloneable         |
--------------------------------
|+clone(): Object              |
--------------------------------
                  ^
                  |
                  |
                  |
--------------------------------
|             Octagon          |
--------------------------------
|-side: double                 |
|+Octagon()                    |
|+Octagon(side: double)        |
|+getSide(): double            |
|+setSide(side: double): void  |
|+getArea(): double            |
|+getPerimeter(): double       |
|+compareTo(octagon: Octagon): int |
|+clone(): Object              |
--------------------------------

以下是 Octagon 类的实现：

public class Octagon extends GeometricObject implements Comparable<Octagon>, Cloneable {
    private double side;

    public Octagon() {
        this(1.0);
    }

    public Octagon(double side) {
        this.side = side;
    }

    public double getSide() {
        return side;
    }

    public void setSide(double side) {
        this.side = side;
    }

    @Override
    public double getArea() {
        return (2 + 4 / Math.sqrt(2)) * side * side;
    }

    @Override
    public double getPerimeter() {
        return 8 * side;
    }

    @Override
    public int compareTo(Octagon o) {
        if (getArea() > o.getArea()) {
            return 1;
        } else if (getArea() < o.getArea()) {
            return -1;
        } else {
            return 0;
        }
    }

    @Override
    public Object clone() throws CloneNotSupportedException {
        return super.clone();
    }
}

以下是测试程序：

public class TestOctagon {
    public static void main(String[] args) {
        Octagon octagon = new Octagon(5);
        System.out.println("Area: " + octagon.getArea());
        System.out.println("Perimeter: " + octagon.getPerimeter());

        try {
            Octagon octagon2 = (Octagon) octagon.clone();
            int result = octagon.compareTo(octagon2);
            if (result == 1) {
                System.out.println("The original octagon has a larger area than the cloned octagon.");
            } else if (result == -1) {
                System.out.println("The cloned octagon has a larger area than the original octagon.");
            } else {
                System.out.println("Both octagons have the same area.");
            }
        } catch (CloneNotSupportedException ex) {
            ex.printStackTrace();
        }
    }
}