继承(Java版本Java只有单继承 多继承是需要通过多态实现的)

圆

package com.wanson.handle_inheritance;

public class Circle {
    private double radius;

    public Circle() {
        this(1.0);
    }

    public Circle(double radius) {
        this.radius = radius;
    }

    public double getRadius() {
        return radius;
    }

    public void setRadius(double radius) {
        this.radius = radius;
    }
    public double findArea(){
        return Math.PI*Math.pow(radius,2);
    }
}

Cylinder

package com.wanson.handle_inheritance;

public class Cylinder extends Circle {
    private double length;

    public Cylinder() {
        super(); //调用父类的默认构造函数
    }

    public Cylinder(double length) {
        this.length = length;
    }

    public Cylinder(double radius, double length) {
        super(radius);
        this.length = length;
    }

    public double getLength() {
        return length;
    }

    public void setLength(double length) {
        this.length = length;
    }

    public double findVolume(){
        return findArea()*length;
    }
}

客户端测试

package com.wanson.handle_inheritance.test;

import com.wanson.handle_inheritance.Circle;
import com.wanson.handle_inheritance.Cylinder;

public class Driver {
    public static void main(String[] args) {
        // 圆的信息
        Circle circle=new Circle();
        System.out.println(circle.getRadius());
        System.out.println(circle.findArea());

        circle.setRadius(100);
        System.out.println(circle.getRadius());
        System.out.println(circle.findArea());

        for (int i = 0; i <20 ; i++) {
            System.out.print("*\t");
        }

//        圆柱的信息
        Cylinder cylinder=new Cylinder();
        System.out.println(cylinder.getLength());
        System.out.println(cylinder.findVolume());

        for (int i = 0; i <20 ; i++) {
            System.out.print("*\t");
        }

        System.out.println();
        Cylinder cylinder1=new Cylinder(5,2);

        System.out.println("圆柱高度:\t"+cylinder1.getLength());
        System.out.println("圆柱半径:\t"+cylinder1.getRadius());
        System.out.println(cylinder1.findVolume());



    }
}