354. 355. 本章作业14 15
Person.java
package com.m.homework13;public class Person {private String name;private int age;private char gender; //性别public Person(String name, int age, char gender) {this.name = name;this.age = age;this.gender = gender;}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 void play(){System.out.print(name + "爱玩");}public char getGender() {return gender;}public void setGender(char gender) {this.gender = gender;}public void printInfo(){System.out.println("姓名：" + name);System.out.println("年龄：" + age);System.out.println("性别：" + gender);}}Student.java
package com.m.homework13;public class Student extends Person {private String stuId; //学号public Student(String name, int age, char gender, String stuId) {super(name, age, gender);this.stuId = stuId;}public String getStuId() {return stuId;}public void setStuId(String stuId) {this.stuId = stuId;}public void study(){System.out.println("我承诺，我会好好学习");}@Overridepublic void play() {super.play();System.out.println("足球");}@Overridepublic void printInfo() {System.out.println("学生的信息：");super.printInfo();System.out.println("学号：" + stuId);}
}Teacher.java
package com.m.homework13;public class Teacher extends Person{private int workAge; //工龄public Teacher(String name, int age, char gender, int workAge) {super(name, age, gender);this.workAge = workAge;}@Overridepublic void printInfo() {System.out.println("老师的信息：");super.printInfo();System.out.println("工龄：" + workAge);}public void teach(){System.out.println("我承诺，我会认真教学");}@Overridepublic void play() {super.play();System.out.println("象棋");}
}Homework13.java
package com.m.homework13;public class Homework13 {public static void main(String[] args) {Person[] persons = new Person[4];persons[0] = new Student("田所浩二", 24, '男', "114514");persons[1] = new Student("波奇酱", 18, '女', "1919" );persons[2] = new Teacher("我修院", 26, '男', 1);persons[3] = new Teacher("德川", 26, '男', 1);Homework13 homework13 = new Homework13();homework13.bubbleSort(persons);homework13.printResults(persons);}//自动转型的方法public void test(Person p){if(p instanceof Student){((Student) p).study();}else if(p instanceof Teacher){((Teacher) p).teach();}}//冒泡排序方法public void bubbleSort(Person[] persons){//冒泡排序按年龄排序Person tmp = null; //冒泡排序用的临时引用//从i到倒数第二个元素，方便给最后一个元素交换for(int i = 0; i < persons.length - 1 ; i++){for(int j = 0; j < persons.length - i - 1; j++){if(persons[j].getAge() > persons[j+1].getAge()){tmp = persons[i];persons[i] = persons[j];persons[j] = tmp;}}}}//打印Person数组信息public void printResults(Person[] persons){//打印数组，使用向下转型for(int i = 0; i < persons.length; i++){System.out.println("-------------------------");if(persons[i] instanceof Student){((Student)persons[i]).printInfo();((Student)persons[i]).study();test(persons[i]);}if(persons[i] instanceof Teacher){((Teacher)persons[i]).printInfo();((Teacher)persons[i]).teach();((Teacher)persons[i]).play();}}}}运行结果：
-------------------------
学生的信息：
姓名：波奇酱
年龄：18
性别：女
学号：1919
我承诺，我会好好学习
我承诺，我会好好学习
-------------------------
学生的信息：
姓名：田所浩二
年龄：24
性别：男
学号：114514
我承诺，我会好好学习
我承诺，我会好好学习
-------------------------
老师的信息：
姓名：我修院
年龄：26
性别：男
工龄：1
我承诺，我会认真教学
我修院爱玩象棋
-------------------------
老师的信息：
姓名：德川
年龄：26
性别：男
工龄：1
我承诺，我会认真教学
德川爱玩象棋
356. 本章作业15
无参构造器先执行this(“hello”)，然后进入有参构造器。
357. 358. 本章作业16 17
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