实例需求：实现一个名为Person的类和它的子类Employee，Manager是Employee的子类，设计一 个类Add()用于涨工资，普通员工一次能涨10%，经理能涨20%。

具体要求如下:
（1）Person类中的属性有：姓名name String（类型），地址address（String类型），定义该类的构造方法；（2）Employee 类中的属性有：工号ID（String类型)，工资wage（double类型），工龄（int 型），定义该类的构造方法；
（3）Manager类中的属性有：级别level（String类型）定义该类的构造方法；
（4）编写一个测试类，产生一个员工和一个经理，给该员工和经理涨工资。

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1、利用继承的特性

当子类没有相应的成员方法时，调用父类的同名方法。
Person.java

package person_employee;

public class Person {
    private String name = "";
    private String address = "";
    //定义构造方法
    public Person(String name, String address){
        this.name = name;
        this.address = address;      
    }
}

Employee.java

package person_employee;
//  继承Person类
public class Employee extends Person {
    private String ID = "";
    private double wage = 0;
    private int age = 0;
    
    public Employee(String name, String address, String ID, double wage, int age){
        super(name, address);  //调用父类的构造方法
        this.ID = ID;
        this.wage = wage;
        this.age = age;
    }

    public double add(String position){//  判断职位
        if(position == "0"){
            wage = wage*1.2;
        }
        else{
            wage = wage*1.1;
        }
        return wage;
    }
        //设置get/set方法
    public double getWage() {
        return wage;
    }
    public void setWage(double wage) {
        this.wage = wage;
    }
}

Manager.java

package person_employee;
//继承Employee类
public class Manager extends Employee{
    private String level = "";  //1为普通员工，0为经理
    
    public Manager(String name, String address, String ID, double wage, int age, String level){
        super(name, address, ID, wage, age);
        this.level = level;
    }
        
        //设置get/set方法
    public String getLevel() {
        return level;
    }

    public void setLevel(String level) {
        this.level = level;
    }
}

Test.java

package person_employee;

public class Test {

    public static void main(String[] args) {
        //  新建对象
        Manager normal = new Manager("wsl", "jit", "12", 1000, 2, "1");
        Manager manager = new Manager("ctl", "jitt", "123", 10000, 10, "0");
        //  传入职位，Manager类型的对象没有add()方法，所以自动搜寻其父类，调用add()方法
        normal.add(normal.getLevel());
        manager.add(manager.getLevel());
        
        System.out.println("normal wage is:"+normal.getWage());
        System.out.println("manager wage is:"+manager.getWage());
    }
}

打印结果：

打印结果

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2、定义抽象类

定义抽象类，在子类中实现不同的抽象方法。

Person.java

package person_employee;

public class Person {
    private String name = "";
    private String address = "";
    //定义构造方法
    public Person(String name, String address){
        this.name = name;
        this.address = address;      
    }
}

Employee.java

package person_employee;

public abstract class  Employee extends Person {
    private String ID = "";
    private double wage = 0;
    private int age = 0;
    
    public Employee(String name, String address, String ID, double wage, int age){
        super(name, address);
        this.ID = ID;
        this.wage = wage;
        this.age = age;
    }
    
    //定义抽象方法
    public abstract void add(String position);
    
    //设置get/set方法
    public double getWage() {
        return wage;
    }
    public void setWage(double wage) {
        this.wage = wage;
    }
}

Manager.java

package person_employee;

public class Manager extends Employee{
    private String level = "";
    
    public Manager(String name, String address, String ID, double wage, int age, String level){
        super(name, address, ID, wage, age);
        this.level = level;
    }
    //实现抽象方法
    public void add(String position){
        double wage = super.getWage();
        if(position == "0"){
            super.setWage(wage*1.2);
        }
        else{
            super.setWage(wage*1.1);;
        }
    }

    public String getLevel() {
        return level;
    }

    public void setLevel(String level) {
        this.level = level;
    }
}

Test.java

package person_employee;

public class Test {

    public static void main(String[] args) {
        Manager normal = new Manager("wsl", "jit", "12", 1000, 2, "1");
        Manager manager = new Manager("ctl", "jitt", "123", 10000, 10, "0");
        
        normal.add(normal.getLevel());
        manager.add(manager.getLevel());
        
        System.out.println("normal wage is:"+normal.getWage());
        System.out.println("manager wage is:"+manager.getWage());
    }
}

打印结果一样。

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3、在2的基础上利用多态实现方法的重载

Manager.java

package person_employee;

public class Manager extends Employee{
    private String level = "";
    
    public Manager(String name, String address, String ID, double wage, int age, String level){
        super(name, address, ID, wage, age);
        this.level = level;
    }
    //实现抽象方法
    public void add(){
        double wage = super.getWage();
        super.setWage(wage*1.1);
    }
    public void add(String position){
        double wage = super.getWage();
        super.setWage(wage*1.2);
    }

    public String getLevel() {
        return level;
    }

    public void setLevel(String level) {
        this.level = level;
    }
}

Test.java

package person_employee;

public class Test {

    public static void main(String[] args) {
        Manager normal = new Manager("wsl", "jit", "12", 1000, 2, "1");
        Manager manager = new Manager("ctl", "jitt", "123", 10000, 10, "0");
        
        normal.add();
        manager.add(manager.getLevel());
        
        System.out.println("normal wage is:"+normal.getWage());
        System.out.println("manager wage is:"+manager.getWage());
    }
}

打印结果一样