java菜鸟求高手指点错误，。。！！

import java.lang.Math;
class circle
{
double PI=3.1415926;
double r;
public circle(double r){
area(r);
}
}
class sphere extends circle
{
public sphere(){
super(r);
area()
{
return 4*PI*r*r;}
bulk(){
return (4/3)*PI*r*r*r;}
}
}
class cylinder extends circle
{
public cylinder(){
super(r);
area(){
return 2*PI*r*h;}
bulk(double r,double h){
return PI*r*r*h;}
}
}
class Coneextends extends circle
{
public taper()
{
super(r);
area(double r,double h){
return PI*r*Math.sqrt(r*r+h*h)+PI*r*r;}
bulk(double r,double h){
return (1/3)*(PI*r*r*h);}
}
}
public class text{
public static void main(String[]agrs){
sphere a=new sphere();
double w1=a.area(2.0);
double w2=a.bulk(2.0);
cylinder b=new cylinder();

import java.lang.Math;
class circle
{
double PI=3.1415926;
double r;
public circle(double r)
{
this.r = r;
}
double area(double r)
{
return PI*r*r;
}
}
class sphere extends circle
{
public sphere(double r)
{
super(r);
}
double area(double r)
{
return 4*PI*r*r;
}
double bulk(double r)
{
return (4/3)*PI*r*r*r;
}
}
class cylinder extends circle
{
public cylinder(double r)
{
super(r);
}
double area(double r, double h)
{
return 2*PI*r*h;
}
double bulk(double r,double h)
{
return PI*r*r*h;
}
}
class Cone extends circle
{
public Cone(double r)
{
super(r);
}
double area(double r, double h)
{
return PI*r*Math.sqrt(r*r+h*h)+PI*r*r;
}
double bulk(double r, double h)

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