Question

java编写一个应用程序，创建一个圆类，在类中定义半径成员变量、求面积和求周长的方法，

在主类中定义圆类对象，根据输入的圆的半径求它的面积和周长。

Answer 1

import java.util.Scanner;
class Round{
public double perimeter(double radius){
return radius*2;
}
public double area(double radius){
return radius*radius*3.14;
}
public void print(double radius){
System.out.println("圆的周长为-->"+this.perimeter(radius)+"\n"+
"圆的面积为-->"+this.area(radius));
}
}
public class OperateDemo{
public static void main(String args[]){
Round round=new Round();
System.out.print("请输入圆的半径-->");
Scanner scan=new Scanner(System.in);
double radius=scan.nextDouble();
round.print(radius);
}
}
楼主别忘了给分呀~~~

Answer 2

class Round{
private static double pi=3.1415926;
private int r;

public Round(int rad){//构造
r = rad;
}
public double GetArea(){
return pi * r * r;
}
public double GetPer(){
return 2*pi*r;
}
}