JAVA编程实现：创建一个图形类，该类里有求体积的方法getV（）

public class Graph {
public double getV() {
return 0;
}
}

// 各种图形的子类，重写getV()方法
public class Cube extends Graph {
private double a;

public Cube(double a) {
this.a = a;
}

@Override
public double getV() {
return a * a * a;
}
}

public class Sphere extends Graph {
private double r;

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

@Override
public double getV() {
return 4.0 / 3.0 * Math.PI * r * r * r;
}
}

public class Cone extends Graph {
private double r;
private double h;

public Cone(double r, double h) {
this.r = r;
this.h = h;
}

@Override
public double getV() {
return 1.0 / 3.0 * Math.PI * r * r * h;
}
}

// 测试用例
public class Main {
public static void main(String[] args) {
Graph cube = new Cube(3);
Graph sphere = new Sphere(4);
Graph cone = new Cone(2, 5);

System.out.println("Cube volume: " + cube.getV());
System.out.println("Sphere volume: " + sphere.getV());
System.out.println("Cone volume: " + cone.getV());
}
}