创建一个圆类Circle的对象，分别设置圆的半径计算并分别显示圆半径、圆面积、圆周长。

package com.Summer_0511.cn;

/**
 * @author Summer
 *
 */
class Circle{
    private double Radius;

    
    public Circle() {    
        super();    
        Radius=0;
    }

    public Circle(double r) {
        super();
        this.Radius = r;
    }
    
    public double getArea(double r){
        double Area = r*r*3.14;
        return Area;
    }
    
    public double getPerimeter(double r){
        double Perimeter = 2*3.14*r;
        return Perimeter;
    }
    
    public void show(double r){
        System.out.println("圆的半径为"+r);
        System.out.println("圆的面积为"+getArea(r));
        System.out.println("圆的周长为"+getPerimeter(r));
    }
    
}
public class Test04 {

    public static void main(String[] args) {
        Circle c = new Circle();
        c.show(3);

    }

}

package stage3;
class Circle{
    private double radius;//半径
    private final double PI = 3.24d;
    public Circle(double radius) {
        this.radius = radius;
    }

    public Circle() {
        this.radius = 0;
    }
    public double getArea() {
        return PI*Math.pow(this.radius, 2);
    }
    public double getPerimeter() {
        return 2* PI * this.radius;
    }
    public void show() {
        System.out.println(this.radius+","+getPerimeter()+","+getArea());
    }
    
}
public class Test2 {

    public static void main(String[] args) {
        
        Circle c = new Circle(2);
        c.show();
    }

}