作业2020.12.15

第十章作业代码

第一题,求面积:

1,父类

package homework01;
    
    //定义抽象类Area
abstract class Area { 
    public abstract double area();//定义抽象方法
}

2,子类1

package homework01;

class RoundArea extends Area{
    private double radius;  //定义半径
    public RoundArea() {
        
    }
    public RoundArea(double radius) {
        this.radius = radius;
    }
    public double area() {
        return Math.PI * this.radius *this.radius;
    }
    public double getRadius() {
        return radius;
    }
    public void setRadius(double radius) {
        this.radius = radius;
    }
    

}

3,子类

package homework01;

//定义矩形子类
public class RectArea extends Area{
    private double length;//定义长度
    private double width;//定义宽度
    public RectArea(){
        
    }
    public RectArea(double length,double width) {
        this.length = length;
        this.width = width;
    }
    public double area(){
        return this.length*this.width;
    }
    public double getLength() {
        return length;
    }
    public void setLength(double length) {
        this.length = length;
    }
    public double getWidth() {
        return width;
    }
    public void setWidth(double width) {
        this.width = width;
    }
}

4,测试类

package homework01;

import java.util.Scanner;

public class Test {
    public void test(){
        Scanner sc = new Scanner(System.in);
        Area a;
        a = new RoundArea();
        System.out.println("请输入圆的半径:");
        ((RoundArea)a).setRadius(sc.nextDouble());
        System.out.println("圆的面积为:" + a.area());
        Area b;
        b = new RectArea();
        System.out.println("请输入长:");
        ((RectArea)b).setLength(sc.nextDouble());
        System.out.println("请输入宽:");
        ((RectArea)b).setWidth(sc.nextDouble());
        System.out.println("长方形的面积为:"+b.area());
    }
    public static void main(String[] args) {
        Test sum = new Test();
        sum.test();
    }
}