Java(八边形类0ctagon)编写一个名为0ctagon 的类，它继承自Geometricobject类并实现Comparable 和Coneable 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)x边长x 边长 画出包括0ctagon、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0tagon 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。

好的，下面是您要求的Octagon类的代码和UML图：

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

    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 (this.getArea() > o.getArea()) {
            return 1;
        } else if (this.getArea() < o.getArea()) {
            return -1;
        } else {
            return 0;
        }
    }

    @Override
    public Octagon clone() {
        Octagon o = new Octagon(this.side);
        return o;
    }
}

UML图如下：

     GeometricObject
    +color: String
    +filled: boolean
    +GeometricObject()
    +GeometricObject(color: String, filled: boolean)
    +getColor(): String
    +setColor(color: String): void
    +isFilled(): boolean
    +setFilled(filled: boolean): void
    +getArea(): double
    +getPerimeter(): double

            |
            |
            v

        Comparable
    +compareTo(o: Object): int

            |
            |
            v

         Cloneable
    +clone(): Object

            |
            |
            v

          Octagon
    +side: double
    +Octagon(side: double)
    +getSide(): double
    +setSide(side: double): void
    +getArea(): double
    +getPerimeter(): double
    +compareTo(o: Octagon): int
    +clone(): Octagon

接下来是测试程序：

public class Test {
    public static void main(String[] args) {
        Octagon o1 = new Octagon(5);
        System.out.println("Octagon 1:\nArea = " + o1.getArea() + "\nPerimeter = " + o1.getPerimeter());

        Octagon o2 = o1.clone();
        int result = o1.compareTo(o2);
        if (result > 0) {
            System.out.println("Octagon 1 is larger than Octagon 2");
        } else if (result < 0) {
            System.out.println("Octagon 1 is smaller than Octagon 2");
        } else {
            System.out.println("Octagon 1 is equal to Octagon 2");
        }
    }
}

输出结果为：

Octagon 1:
Area = 120.71067811865476
Perimeter = 40.0
Octagon 1 is equal to Octagon 2

其中，Octagon 2 是用 clone 方法创建的一个新的 Octagon 对象。由于两个对象的面积相等，所以 compareTo 方法返回值为 0。