韩顺平-多态的应用及动态绑定机制

package Poly_.PolyArray;

public class Polyarray {
    public static void main(String[] args) {
        Person[] persons=new Person[5];
        persons[0]=new Person("jack",20);
        persons[1]=new Students("tom",18,100);
        persons[2]=new Students("xiaoma",20,99);
        persons[3]=new Teacher("wang",35,7000);
        persons[4]=new Teacher("scot",40,20000);

        for (int i=0;i

• 1
• 2
• 3
• 4
• 5
• 6
• 7
• 8
• 9
• 10
• 11
• 12
• 13
• 14
• 15
• 16
• 17
• 18
• 19
• 20
• 21
• 22
• 23
• 24
• 25

📚 Person类

package Poly_.PolyArray;

public class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
    public String say(){
        return "名字 "+name+" 年龄= "+age;
    }


    }

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33

📚 Students类

package Poly_.PolyArray;

public class Students extends Person {
    private double score;

    public Students(String name, int age, double score) {
        super(name, age);
        this.score = score;
    }

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }

    @Override
    public String say() {
        return super.say()+" 成绩="+score;
    }
    public void study(){
        System.out.println("学生"+getName()+"正在听课");
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

📚 Teacher类

package Poly_.PolyArray;

public class Teacher extends Person{
    private double salary;

    public Teacher(String name, int age, double salary) {
        super(name, age);
        this.salary = salary;
    }

    public double getSalary() {
        return salary;
    }

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

    @Override
    public String say() {
        return super.say()+" salary="+salary;
    }
    public void teach(){
        System.out.println("老师"+getName()+"正在讲课");
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

📈结果：

📌例题2

📚 Employee类

创建属性，名字和薪资

创建构造器

创建get和set方法

package Poly_.PolyParameter;

public class Employee {
    private  String name;
    private double salary;

    public Employee(String name, double salary) {
        this.name = name;
        this.salary = salary;
    }
    public  double getAnnual(){
        return 12*salary;
}
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getSalary() {
        return salary;
    }

    public void setSalary(double salary) {
        this.salary = salary;
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29

📚 Worker类

继承父类Employee的名字和薪资

创建构造器

创建work方法,get父类的私有属性Annual

package Poly_.PolyParameter;
public class worker extends Employee {
    public worker(String name, double salary) {
        super(name, salary);
    }
    public void work(){
        System.out.println("  普通员工  "+getName()+"  正在工作....  ");
    }

    @Override
 //普通员工没有其他方法，直接调用父类方法
    public double getAnnual() {
        return super.getAnnual();
    }
}
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15

📚 Manager类

继承父类Employee的名字和薪资,创建自己的私有属性bouns;

创建构造器;

创建mange方法,get父类的私有属性Annua并且联合自己的bouns属性;

package Poly_.PolyParameter;

public class Manager extends Employee {
    private double bouns;
    public Manager(String name, double salary, double bouns) {
        super(name, salary);
        this.bouns = bouns;
    }

    public double getBouns() {
        return bouns;
    }

    public void setBouns(double bouns) {
        this.bouns = bouns;
    }
    public void manag(){
        System.out.println("经理 "+getName()+" 正在管理 ....");
    }

    @Override
    public double getAnnual() {
    //获取他的基本工资(从父类)，并且加上他的奖金才是年薪
        return super.getAnnual()+bouns;
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27

📚 Test类(父类)

package Poly_.PolyParameter;

import javafx.concurrent.Worker;

public class Test {
    public static void main(String[] args) {
    worker w=new worker("tom",2000);
    Manager manager=new Manager("米兰",5000,50000);
    Test test=new Test();
    test.showEmployAnnual(w);
    //传进去的manag会跟Manger绑定，有动态绑定机制，调用的是经理方法
    test.showEmployAnnual(manager);
    test.testwork(w);
    test.testwork(manager);
    }
    public void showEmployAnnual(Employee e ){
    //传进来是什么员工，就会调用相应员工的薪资
        System.out.println(e.getAnnual());
    }
    public void testwork(Employee e){
    //看其编译类型是什么，如果是普通工人，就将其转为worker方法
        if (e instanceof worker){
            ((worker)e).work()//向下转型
        }else if (e instanceof Manager){//如果 是manager就将其转为Manager方法
            ((Manager)e).manag();
        }
    }
}

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30

传进去w，运行对象为worker,执行
传进去manger，运行对象为Manager,执行

test.testwork(w);
test.testwork(manager);
}
public void showEmployAnnual(Employee e ){
//传进来是什么员工，就会调用相应员工的薪资
System.out.println(e.getAnnual());
}
public void testwork(Employee e){
//看其编译类型是什么，如果是普通工人，就将其转为worker方法
if (e instanceof worker){
((worker)e).work()//向下转型
}else if (e instanceof Manager){//如果 是manager就将其转为Manager方法
((Manager)e).manag();
}
}
}

📈结果：