package jiekou1;public interface ShapePara {     //定义常量PI    final double PI=3.14;     //定义抽象方法     //获得图形面积    double getArea();        //获得图形周长    double getCircumference();    }

package jiekou1;public class Circle implements ShapePara {    //定义成员变量    public double radius;    public double x;    public double y;            //定义构造方法    Circle(double radius)    {        this.radius=radius;        this.x=0;        this.y=0;    }        //定义成员方法    //返回半径的值    double getRadius()    {        return radius;    }        //写入圆心的坐标    void setCenter(double x, double y)    {        this.x=x;        this.y=y;    }            //写入圆的半径    void setRadius(double radius)    {        this.radius=radius;    }        //完善得到面积和周长的方法    @Override    public double getArea() {                return PI*radius*radius;    }    @Override    public double getCircumference() {                return 2*PI*radius;    }}

package jiekou1;public class Shape {    //成员变量    private ShapePara sp;            public ShapePara getSp() {        return sp;    }    public void setSp(ShapePara sp) {        this.sp = sp;    }    //定义成员方法获得图形面积    void getArea()    {        System.out.println(sp.getArea());    }    //定义成员方法获得图形周长    void getCircumference()    {        System.out.println(sp.getCircumference());    }}

package jiekou1;public class Rect extends Shape{     //定义成员变量    private double a;    private double b;    public double getA() {        return a;    }    public void setA(double a) {        this.a = a;    }    public double getB() {        return b;    }    public void setB(double b) {        this.b = b;    }            void getArea()    {        System.out.println("矩形的面积为："+a*b);    }    }

package jiekou1;public class Text_mianji {    public static void main(String[] args) {                        Shape yy= new Shape();                //匿名对象        Circle cl= new Circle(5);        cl.setCenter(0, 1);        cl.setRadius(12);        yy.setSp(cl);        System.out.println("圆的圆心坐标为：("+cl.x+","+cl.y+")");        System.out.println("半径为："+cl.radius);        System.out.print("圆的面积为：");        yy.getArea();        System.out.print("圆的周长为：");        yy.getCircumference();                        //实例化矩形对象        Rect re = new Rect();        re.setA(20);        re.setB(12.5);        System.out.println("矩形的长为："+re.getA()+"   矩形的宽为："+re.getB());        re.getArea();                                                            }}