继承练习

练习一：

ManKind：

package com.aff.ex1;

//定义一个ManKind类，包括成员变量int sex， int salary
//方法 void manOrWoman();   根据sex的值显示man： sex == 1 ， woman：sex == 0
//方法 void employees()，  根据salary的值显示no  job： salary == 0 ， job：salary != 0;
public class ManKind {
    private int sex;
    private int salary;

    public int getSex() {
        return sex;
    }

    public void setSex(int sex) {
        this.sex = sex;
    }

    public int getSalary() {
        return salary;
    }

    public void setSalary(int salary) {
        this.salary = salary;
    }

    public void manOrWoman() {
        if (sex == 1) {
            System.out.println("Man");
        } else if (sex == 0) {
            System.out.println("Woman");
        } else {
            System.out.println("输入有误");
        }
    }

    public void employees() {
        if (salary == 0) {
            System.out.println("no job");
        } else if (sex > 0) {
            System.out.println("job");
        }
    }
}

Kids：

package com.aff.ex1;

//定义类Kids继承ManKind，并包括成员变量int  yearsOld；
//方法printAge()打印yearsOld的值
public class Kids extends ManKind {
    private int yearsOld;

    public int getYearsOld() {
        return yearsOld;
    }

    public void setYearsOld(int yearsOld) {
        this.yearsOld = yearsOld;
    }

    public void printAge() {
        System.out.println(this.yearsOld + "years old");
    }

}

TestKids：

package com.aff.ex1;

//在kid类的main方法中实例化Kid的对象someKid，
//用该对象访问其父类的成员变量及方法
public class TestKids {
    public static void main(String[] args) {

        Kids someKid = new Kids();
        someKid.setSalary(0);
        someKid.setSex(1);
        someKid.setYearsOld(13);

        someKid.employees();
        someKid.manOrWoman();
        someKid.printAge();
    }
}

输出结果：

no job
Man
13years old

练习二：

Circle：

package com.aff.ex1;

public class Circle {
    private double radius;

    public Circle() {
        this.radius = 1;
    }

    public double getRadius() {
        return radius;
    }

    public void setRadius(double radius) {
        this.radius = radius;
    }

    // 计算圆的面积
    public double findArea() {
        return Math.PI * radius * radius;
    }

}

Cylinder：

package com.aff.ex1;

//圆柱：是对圆的扩展
public class Cylinder extends Circle {
    private double length;// 圆柱的高

    public Cylinder() {
        length = 1;
    }

    public double getLength() {
        return length;
    }

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

    // 圆柱的体积
    public double findVolum() {
        return findArea() * length;
        // return Math.PI * this.getRadius() * this.getRadius() * length;
    }
}

TestCylinder：

package com.aff.ex1;

public class TestCylinder {
    public static void main(String[] args) {

        Cylinder c = new Cylinder();
        System.out.println(c.findVolum());

        c.setLength(1.2);
        c.setRadius(2.3);
        System.out.println(c.findVolum());
    }
}

输出结果：

3.141592653589793
19.942830164988003