继承与多态的一个简单实例
程序结构：
父为Person类,Person类个子类Student和Employee，Employee类又有两个子类，Staff和Faculty。
继承即子类可以继承父类的数据域和方法：
Student类和Employee类继承了Person类的数据域name，address phoneNumber E_mail className 以及他们的set方法和get方法。同时Emloyee类中声明了新的数据域office，wage，date以及他们的set get方法。Student类有新的grade数据域和方法。
Staff和Faculty类继承了Employee类中的所有方法，包括从Person类中继承来的方法，同时有定义了自己的新方法。
同时，子类通过super调用了父类设置日期的构造方法和toString方法。
多态：
TestPerson类中创建了Student，Staff和Faculty类型的对象
在调用toString时，每个类都有自己对toString方法的实现（子类覆盖了父类的toString方法），最终的输出结果取决于对象的类型，体现了动态绑定。
package person;
//父类
public class Person {
protected String name ; //姓名
protected String address; //地址
protected String phoneNumber; //电话号码
protected String E_mail; //电子邮件
protected String className; //类名，即学生、职员、教员
public void setE_mail() {
this.E_mail=E_mail;
}
public String getE_mail() {
return E_mail;
}
public void setPhoneNumber() {
this.phoneNumber=phoneNumber;
}
public String getPhoneNumber() {
return phoneNumber;
}
public void setClassName() {
this.className=className;
}
public String getClassName() {
return className;
}
public void setAddress() {
this.address=address;
}
public String getAddress() {
return address;
}
public void setName() {
this.name=name;
}
public String getName() {
return name;
}
public String toString() {
return getClassName()+" \n"+getName()+" \nphnone number is:\n"+getPhoneNumber()+" \nE-mail is :\n"+getE_mail()+" \naddress is :\n"+getAddress();
}
}
package person;
public class Student extends Person{
protected String grade;
final static int RRESHMAN=1;
final static int SOPHOMORE=2;
final static int JUNIOR=3;
final static int SENIOR=4;
public void setGrade() {
this.grade=grade;
}
public String getGrade() {
return grade;
}
public Student(String className,String name,String grade,String phoneNumber,String E_mail,String address) {
this.className=className;
this.name=name;
this.grade=grade;
this.phoneNumber=phoneNumber;
this.E_mail=E_mail;
this.address=address;
}
public String toString() {
return super.toString()+"\ngrade is :\n"+grade;
}
}
package person;
public class Employee extends Person {
protected String office; //办公室
protected double wage; //工资
MyDate date; //MyDate的一个对象，作用是在employee里面创建一个构造方法，使在子类中能调用他的构造方法
public Employee(int year,int month,int day) {
this.date=new MyDate(year,month,day);
}
public void setOffice() {
this.office=office;
}
public String getOffice() {
return office;
}
public void setWage() {
this.wage=wage;
}
public double getWage() {
return wage;
}
public String toString() {
return super.toString()+"\noffice is :\n"+getOffice()+"\nwage is :\n"+getWage()+"\nthe year is :\n"+MyDate.getYear()+
"\nthe month is:\n"+MyDate.getMonth()+"\nthe day is:\n"+MyDate.getDay();
}
}
package person;
//教员
public class Faculty extends Employee {
protected String rank; //等级
protected String time; //工作时间如9:00-13:00
public void setRank() {
this.rank=rank;
}
public String getRank() {
return rank;
}
public void setTime() {
this.time=time;
}
public String getTime() {
return time;
}
public Faculty(String className,String name,String rank,String phoneNumber,String E_mail,String address,String office,double wage,String time,int year,int month,int day){
super(year,month,day);
this.className=className;
this.name=name;
this.rank=rank;
this.phoneNumber=phoneNumber;
this.E_mail=E_mail;
this.address=address;
this.office=office;
this.wage=wage;
this.time=time;
}
public String toString() {
return super.toString()+"\nrank is :\n"+rank+"\nthe work time is:\n"+time;
}
}
package person;
//职员
public class Staff extends Employee {
protected String staffTitle; //职位
public void setStaffTitle() {
this.staffTitle=staffTitle;
}
public String getStaffTitle() {
return staffTitle;
}
public Staff(String className,String name,String staffTitle,String phoneNumber,String E_mail,String address,String office,double wage,int year,int month,int day) {
super(year,month,day);
this.className=className;
this.name=name;
this.staffTitle=staffTitle;
this.phoneNumber=phoneNumber;
this.E_mail=E_mail;
this.address=address;
this.name=name;
this.office=office;
this.wage=wage;
}
public Staff() { //无参的构造方法，默认方法
this("staff","lisi","cleaner","1527319","[email protected]","北京市","机械院203",3000,2015,3,12);
}
public String toString() {
return super.toString()+"\nstaffTitle is :\n"+staffTitle;
}
}
package person;
public class MyDate {
public static int year;
public static int month;
public static int day;
public MyDate(int year,int month,int day) {
this.year=year;
this.month=month;
this.day=day;
}
public void setYear() {
this.year=year;
}
public static int getYear() {
return year;
}
public void setMonth() {
this.month=month;
}
public static int getMonth() {
return month;
}
public void setDay() {
this.day=day;
}
public static int getDay() {
return day;
}
}
package person;
public class TestPerson {
public static void main(String[] args) {
m(new Student("student","zengmeng","junior","12345","[email protected]","四川成都")); //初始化学生对象
m(new Faculty("Faculty","zhangsan","associate professor","139822","[email protected]","湖南长沙","环境院408",10000,"9:00-18:00",2018,6,20));
m(new Staff()); //初始化职员对象，无参构造
}
public static void m(Object x) {
System.out.println(x.toString()); //输出
}
}
运行结果
