圆类，成员半径r（double）,getPerimeter计算周长，Area面积

[java]代码库

import java.util.Scanner;
public class Main{
	public static void main(String[] args) {
         Scanner scan = new Scanner(System.in);
         double r_c1 = scan.nextDouble();      
         double r_c2 = scan.nextDouble();      
         scan.close();      
         Circle c1 = new Circle();      
         c1.setR(r_c1);         
         System.out.println(c1.getArea()); 
         System.out.println(c1.getPerimeter());      
         Circle c2 = new Circle(r_c2);      
         System.out.println(c2.getArea());         
         System.out.println(c2.getPerimeter());   
 
    }
} 

class Circle {
	private double r;
	public Circle() {
		r = 0;
	}
	public Circle(double _r) {
		r = _r;
	}
	public void setR(double _r) {
		r = _r;
	}
	public double getPerimeter() {
		double p = 2*3.14*r;
		return p;
	}
	public double getArea() {
		double a = 3.14*r*r;
		return a;
	}
}