用接口实现以下UML图,java测试类中，有三个柱体，分别以三角形，圆形，矩形为底面积，求它们的体积。pillar类连接Geometry接口 。测试用例：:三角形边：（3，4，5）;圆形半径：2; 矩形边（3，4），柱体高：6.

以下是实现UML图的Java代码：

// Geometry接口
interface Geometry {
    double getArea();
}

// Circle类
class Circle implements Geometry {
    private double radius;

    public Circle(double radius) {
        this.radius = radius;
    }

    public double getArea() {
        return Math.PI * radius * radius;
    }
}

// Rectangle类
class Rectangle implements Geometry {
    private double length;
    private double width;

    public Rectangle(double length, double width) {
        this.length = length;
        this.width = width;
    }

    public double getArea() {
        return length * width;
    }
}

// Triangle类
class Triangle implements Geometry {
    private double a;
    private double b;
    private double c;

    public Triangle(double a, double b, double c) {
        this.a = a;
        this.b = b;
        this.c = c;
    }

    public double getArea() {
        double p = (a + b + c) / 2;
        return Math.sqrt(p * (p - a) * (p - b) * (p - c));
    }
}

// Pillar类
class Pillar {
    private Geometry bottom;
    private double height;

    public Pillar(Geometry bottom, double height) {
        this.bottom = bottom;
        this.height = height;
    }

    public double getVolume() {
        return bottom.getArea() * height;
    }
}

// 测试类
public class Test {
    public static void main(String[] args) {
        Circle circle = new Circle(2);
        Rectangle rectangle = new Rectangle(3, 4);
        Triangle triangle = new Triangle(3, 4, 5);

        Pillar pillar1 = new Pillar(circle, 6);
        Pillar pillar2 = new Pillar(rectangle, 6);
        Pillar pillar3 = new Pillar(triangle, 6);

        System.out.println("圆柱体的体积为：" + pillar1.getVolume());
        System.out.println("矩形柱体的体积为：" + pillar2.getVolume());
        System.out.println("三角形柱体的体积为：" + pillar3.getVolume());
    }
}

输出结果为：

圆柱体的体积为：75.39822368615503
矩形柱体的体积为：72.0
三角形柱体的体积为：36.0