java利用接口计算圆的面积

文档关系

接口代码

package Area;

public interface Area {
    double area();
}

接口子类代码

package Area;

public class areaimpl implements Area{
    private Double r;

    public Double getR() {
	return r;
    }
    public void setR(Double r) {
	this.r = r;
    }
    @Override
    public double area() {
	// TODO Auto-generated method stub
	return (3.14 * getR() * getR());
	
    }
}

测试类代码

package Area;

import java.util.Scanner;

public class Areademo {

    public static void main(String[] args) {
	// TODO Auto-generated method stub
	Scanner sc = new Scanner(System.in);
	System.out.println("--------计算圆形的面积-------");
	System.out.print("请输入圆形的半径：");
	areaimpl r = new areaimpl();
	Double r1 = sc.nextDouble();
	r.setR(r1);
	System.out.println("半径为"+r.getR()+"的圆面积为"+r.area());
	
	

    }

}

运行结果展示