多态的应用

一：多态数组，对象数组

数组的定义类型父类类型，里面保存的实际元素魏子类类型

1：应用实例

public class arrtest00 {
    public static void main(String[] args) {
        //对象数组
        Person[] person = new Person[5];
        //意味着person以及person的子类都可以放进去
        person[0] = new Person("sakura",18);
        person[1] = new Teacher("Tom",50,25000);
        person[2] = new Student("jack",20,100);
        for (int i = 0; i < 3; i++) {
            System.out.println(person[i].say());
            //如何调用子类的特有方法
            if (person[i] instanceof Student){
              //  Student student = (Student) person[i];//向下转型
                ((Student)person[i]).study();//匿名对象的向下转型
            }else if (person[i] instanceof Teacher){
                ((Teacher)person[i]).teach();
            }
        }
    }
}
package Date0802.Test00;
/**
 * 作者：sakura
 * 日期：2022年08月03日 11:59
 */
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   "name:"+this.name + "\t"+"age:"+ this.age;
    }
}
package Date0802.Test00;
/**
 * 作者：sakura
 * 日期：2022年08月03日 11:59
 */
public class Student extends Person{
    private int Score;
    public Student(String name, int age, int score) {
        super(name, age);
        Score = score;
    }
    public int getScore() {
        return Score;
    }
    public void setScore(int score) {
        Score = score;
    }
    @Override
    public String say() {
        return "(学生)"+super.say() +"\t"+ "score:"+"\t"+this.Score;
    }
    public void study(){
        System.out.println("学生:"+getName()+"正在学习");
    }
}
package Date0802.Test00;
/**
 * 作者：sakura
 * 日期：2022年08月03日 12:00
 */
public class Teacher extends Person{
    private int salary;
    public Teacher(String name, int age, int salary) {
        super(name, age);
        this.salary = salary;
    }
    public int getSalary() {
        return salary;
    }
    public void setSalary(int salary) {
        this.salary = salary;
    }
    @Override
    public String say() {
        return "(老师)"+super.say() +"\t"+ "salary:" + this.salary;
    }
    public void teach(){
        System.out.println("老师："+ getName()+ "正在授课");
    }
}

二：多态参数

1：应用举例

package Date0802.Test01;
/**
 * 作者：sakura
 * 日期：2022年08月03日 15:02
 */
public class Test01 {
    public static void main(String[] args) {
        staff tom = new staff("tom", 5000);
        Managerment sakura = new Managerment("sakura", 10000, 9999);
        Test01 T = new Test01();
        T.showEmpAnn(sakura);
        T.showEmpAnn(tom);
        T.testWork(sakura);
        T.testWork(tom);
    }
    public void showEmpAnn(Employee E){
        E.getAnnual();
    }
    public void testWork(Employee E){
        if (E instanceof staff){
            ((staff)E).work();
        }else if(E instanceof Managerment){
            ((Managerment)E).manager();
        }
    }
}

package Date0802.Test01;
/**
 * 作者：sakura
 * 日期：2022年08月03日 14:49
 */
public class Employee {
    private String name;
    private int salary;
    public Employee(String name, int salary) {
        this.name = name;
        this.salary = salary;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getSalary() {
        return salary;
    }
    public void setSalary(int salary) {
        this.salary = salary;
    }
    public void getAnnual(){
        System.out.println(12*getSalary());
    }
}

package Date0802.Test01;
/**
 * 作者：sakura
 * 日期：2022年08月03日 15:00
 */
public class Managerment extends Employee{
    private int bonus;
    public Managerment(String name, int salary, int bonus) {
        super(name, salary);
        this.bonus = bonus;
    }
    public int getBonus() {
        return bonus;
    }
    public void setBonus(int bonus) {
        this.bonus = bonus;
    }
    @Override
    public void getAnnual() {
        System.out.print("经理的"+getName()+"年工资：");
        super.getAnnual();
    }
    public void manager(){
        System.out.println("经理管理员工");
    }
}

package Date0802.Test01;
/**
 * 作者：sakura
 * 日期：2022年08月03日 14:55
 */
public class staff extends Employee{
    public staff(String name, int salary) {
        super(name, salary);
    }
    public void work(){
        System.out.println("员工工作");
    }
    @Override
    public void getAnnual() {
        System.out.print("员工"+getName()+"的年工资：");
        super.getAnnual();
    }
}