写一个Copyable接口，计算长方体，圆柱体，球体的体积

好的，下面是一个可能的实现：

public interface Copyable {
    double getVolume();
    Copyable copy();
}

public class Cuboid implements Copyable {
    private double length;
    private double width;
    private double height;

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

    @Override
    public double getVolume() {
        return length * width * height;
    }

    @Override
    public Copyable copy() {
        return new Cuboid(length, width, height);
    }
}

public class Cylinder implements Copyable {
    private double radius;
    private double height;

    public Cylinder(double radius, double height) {
        this.radius = radius;
        this.height = height;
    }

    @Override
    public double getVolume() {
        return Math.PI * radius * radius * height;
    }

    @Override
    public Copyable copy() {
        return new Cylinder(radius, height);
    }
}

public class Sphere implements Copyable {
    private double radius;

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

    @Override
    public double getVolume() {
        return 4.0 / 3.0 * Math.PI * Math.pow(radius, 3);
    }

    @Override
    public Copyable copy() {
        return new Sphere(radius);
    }
}

这里定义了一个 `Copyable` 接口，它包括两个方法：`getVolume()` 返回体积，`copy()` 返回一个与当前对象相同的新对象。然后定义了三个实现了 `Copyable` 接口的类，分别表示长方体、圆柱体和球体。每个类都实现了 `getVolume()` 和 `copy()` 方法，通过这些方法可以计算出体积并创建新的对象。