Circle

import java.util.Scanner;

public class Circle {
	public double getRadius() {
		return radius;
	}

	public void setRadius(double radius) {
		this.radius = radius;
	}

	double radius;
	
	Circle() {
		this(1);
	}
	
	Circle(double r) {
		this.radius=r;
	}
	
	public double area(double radius) {
		return Math.PI*radius*radius;
	}
	
	public String toString() {
		return ("circle's radius:"+this.radius+" circle's area:"+this.area(radius));
	}
	
	public static void main(String[] args) {
		Scanner cin=new Scanner(System.in);
		System.out.println("请输入半径 ");
		double r=cin.nextDouble();
		Circle cc=new Circle(r);
		System.out.println(cc.toString());
	}
}