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。 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.

以下是用接口实现UML图的Java代码，其中Triangle、Circle和Rectangle类实现了Geometry接口，并分别计算了它们的体积：

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

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

    public Triangle(double a, double b, double c) {
 this.a = a;
        this.b = b;
        this.c c;
        this.p = (a + b + c) / 2;
    }

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

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

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

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

// Rectangle类
class Rectangle implements Geometry {
    private double a, b;

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

    public double getArea() {
        return a * b;
    }
}

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

        double volume1 = triangle.getArea() * 6;
        double volume2 = circle.getArea() * 6;
        double volume3 = rectangle.getArea() * 6;

        System.out.println("三角形柱体的体积为：" + volume1);
        System.out.println("圆形柱体的体积为：" + volume2);
        System.out.println("矩形柱体的体积为：" + volume3);
    }
}

输出结果为：

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