我是新手，刚学的．不知道这个程序错在哪了．．请高手指点！！谢谢．不胜感激～





class yuan
{
int b;
final double PI=3.1415926;

int mianji()
{
return (int)(PI*((double)b)*((double)b);
}
int zhouchang()
{
return (int)(2*((double)b)*PI);
}
public static void main( String[] args)
{

yuan y1=new yuan();
yuan y2=new yuan();
y1.b=2;
System.out.println("mianji of yuan="+y1.mianji());
System.out.println("zhouchang of yuan="+y1.zhouchang());
y2.b=4;
System.out.println("mianji of yuan="+y2.mianji());
System.out.println("zhouchang of yuan="+y2.zhouchang());
}
}

[此贴子已经被作者于2007-9-22 2:52:29编辑过]

谢谢楼上，我改了后，怎么运行它提示这个：
Exception in thread "main" java.lang.NoSuchMethodError: main
哪的错？

没有啊．不可能错的．谢谢你咯．在帮我找找问题～

是啊，我运行也是得

mianji of yuan=8494
zhouchang of yuan=326
mianji of yuan=50
zhouchang of yuan=25
怎么回事咯．．．

import java.io.*;
class yuan
{
int b;
final double PI=3.1415926;

int mianji()
{
return (int)(PI*((double)b)*((double)b));
}
int zhouchang()
{
return (int)(2*((double)b)*PI);
}

public static void main(String[] args)throws IOException
{

yuan y1=new yuan();
yuan y2=new yuan();
//int c;
System.out.print("shuru:");
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
int c= Integer.parseInt(reader.readLine());
//System.out.println("shuru:");
/* c=System.in.read();*/
y1.b=c;
System.out.println("mianji of yuan="+y1.mianji());
System.out.println("zhouchang of yuan="+y1.zhouchang());
y2.b=c;
System.out.println("mianji of yuan="+y2.mianji());
System.out.println("zhouchang of yuan="+y2.zhouchang());
}
}
呵呵．．谢谢大家的帮助咯．我现在弄明白了．这个程序就ＯＫ了．