已知employee员工是超类，manager经理是子类

manager—>employee

set方法给属性赋值，get方法取得值

1、超类Employee.java
定义属性private私有—》构造方法初始化对象—》用get方法取得值—》LocalDate在JDK1.8中，新增了处理日期的类
LocalDate.of(int year, int month, int dayOfMonth) 根据参数设置日期，参数分别为年，月，日

package com.em;//import java.util.Date;import java.time.LocalDate;public class Emlpoyee {    private String name;    private double salary;    private LocalDate dateday;    public Emlpoyee(String namae,double salary,int year,int month,int day){        this.name = namae;        this.salary = salary;//        this.dateday = dateday;        dateday = LocalDate.of(year,month,day);    }    public String getName() {        return name;    }    public double getSalary() {        return salary;    }    public LocalDate getDateday() {        return dateday;    }}

2、子类Manager.java
定义属性private私有—》构造方法初始化对象—》set方法赋值属性extra—》get方法获取超类的getSalary()，这里不能直接返回想要的值 return salary2 + extra; 这会报错的 —原因是 我文章36.继承私有域的理解
—》解决 借助接口 + super
所以是 double salary2 = super.getSalary();return salary2 + extra;

package com.em;//import java.util.Date;public class Manager extends Emlpoyee{    private double extra;    public Manager(String namae,double salary,int year,int month,int day){        super(namae,salary,year,month,day);//        super(namae, salary, dateday);        extra = 0; //默认值    }    public double getSalary() {//        double salary2 = getSalary();//不能        double salary2 = super.getSalary();        return salary2 + extra;    }    public void setExtra(double extra) {        this.extra = extra;    }}

3、测试类 Test.java
用子类Manager创建对象（new）并赋值—》该对象调用Manager里面赋好值的set方法—》用超类Employee创建对象（new）并赋值，第一个由于后面要循环遍历出来，用上面那个Manger创建好的值—》for(Employee e : staff)把数组循环遍历出来—》sout+e.get方法
另一种方式遍历
for (int i = 0; i < arr.length; i++){
System.out.println(arr[i]);}

package com.em;public class Test {    public static void main(String[] args) {        Manager mange = new Manager("xiaoming",80000,2020,1,2);        mange.setExtra(19999);        Emlpoyee[] emlpoyees = new Emlpoyee[3];        emlpoyees[0] = mange;        emlpoyees[1] = new Emlpoyee("xiaozhang",80000,2020,1,3);        emlpoyees[2] = new Emlpoyee("xiaohua",60000,2020,1,3);        for (Emlpoyee e : emlpoyees){            System.out.println("name=" + e.getName() +",salary=" + e.getSalary() + ",date=" + e.getDateday());        }    }}

4、运行结果：

name=xiaoming,salary=99999.0,date=2020-01-02name=xiaozhang,salary=80000.0,date=2020-01-03name=xiaohua,salary=60000.0,date=2020-01-03