1.编写一个接口ShapePara，要求： 接口中的方法： double getArea()：获得图形的面积。double getCircumference()：获得图形的周长 编写一个圆

Posted 2020-08-09 HRZJ

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();
                
        
        
        
        
        

    }

}