泳池圆的周长和圆环面积

半径为r，圆环半径为3m，已知最外边砌8元/米的围墙，圆环做过道10元/平方米，求造价。

package day141020;

/**
 * 圆类
 * @author XWJ
 *
 */
public class Circle {
	private double radius;		// 半径
	
	/**
	 * 构造器
	 * @param radius 圆的半径
	 */
	public Circle(double radius) {
		this.radius = radius;
	}
	
	/**
	 * 计算面积
	 * @return
	 */
	public double getArea() {
		return Math.PI * radius * radius;
	}
	
	/**
	 * 计算周长
	 * @return
	 */
	public double getCircumference() {
		return 2 * Math.PI * radius;
	}
}

package day141020;

import java.util.Scanner;

public class CircleRun {
	private static final double FP = 8.5;
	private static final double CP = 12;
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		System.out.print("请输入游泳池的半径: ");
		if(sc.hasNextDouble()) {
			double r = sc.nextDouble();
			Circle small = new Circle(r);
			Circle big = new Circle(r + 3);
			System.out.printf("围墙的造价为: ￥%.1f元\n", FP * big.getCircumference());
			System.out.printf("过道的造价为: ￥%.1f元\n", CP * (big.getArea() - small.getArea()));
		}
		else {
			System.out.println("输入错误!!!");
		}
		sc.close();
	}
}