20220723 第一组 于芮 父类与子类的继承2（第十五天）

 

小白成长记——第十五天

 

   今天结束了面向对象中的继承的学习，总体来说，知识还是不够巩固，还需要多加理解，经过了两天的学习，更加的了解了面向对象的含义，经过两天的学习，可以发现自己的逻辑漏洞，每天都有新的知识，对编程的世界更加了解，来看看今天的学习笔记吧！

protected受保护的
final关键字（最终的，终极的）
final可修饰的结构
1.类 public final class
最终类，终极类，不能被继承
2.属性 private final string name
常量，不能重新赋值，不能只声明不赋值
常量的命名规则（单词所有字母大写，如果是多个单词，用下划线分割）
3.方法 private void show
不可以被子类重写

方法重写：标明注解@（@override ）

object（祖先类，最顶级的父类）---11个方法
如果一个类没有明确写出父类是谁，默认继承父类就是object
1.hostcode；
public native int hostcode（）；
返回值是对象运行时的内存地址。
2.equals（）；和双等号一样，比地址
integer中有一个缓冲区，把byte范围内的数存起来了
3.tostring（）；转换成字符串--全类名（有包）
当我们直接使用对象时，默认调用tostring方法，为了让子类重写
4.finalize（）；垃圾回收的方法
5.clone（）；克隆，必须实现cloneable接口

    看了今天的学习笔记，当然还有一个实际的案例，今天的案例我们做了一个简单的教务系统，通过今天的案例，来巩固今天的知识，看看这个案例吧！

public class Demo {
    public static void main(String[] args) {
        Teacher teacher = new Teacher("xyz",40,"789789","8001");
        Student s1 = new Student("aaa",20,"123456","1001",teacher);
        Student s2 = new Student("bbb",20,"123457","1002",teacher);
        Student s3 = new Student("ccc",20,"123458","1003",teacher);
        Student s4 = new Student("ddd",20,"123459","1004",teacher);
        Student s5 = new Student("eee",20,"123450","1005",teacher);
        Student [] stus = new Student[]{s1,s2,s3,s4,s5};
        teacher.setStudents(stus);
        Teacher teacher2 = new Teacher("qwer",40,"456456","8002");
        Student s6 = new Student("fff",22,"223456","2001",teacher2);
        Student s7 = new Student("ggg",22,"223457","2002",teacher2);
        Student s8 = new Student("hhh",22,"223458","2003",teacher2);
        Student s9 = new Student("iii",22,"223459","2004",teacher2);
        Student s10 = new Student("jjj",22,"223450","2005",teacher2);
        Student [] stus2 = new Student[]{s6,s7,s8,s9,s10};
        teacher2.setStudents(stus2);

        Teacher [] teachers = new Teacher[]{teacher,teacher2};
        Student [] students = new Student[]{s1,s2,s3,s4,s5,s6,s7,s8,s9,s10};

        School school = new School();
        school.setTeachers(teachers);
        school.setStudents(students);

//        school.showTeachers();
        school.showStudents();






    }
}

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

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

    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 getCardID() {
        return cardID;
    }

    public void setCardID(String cardID) {
        this.cardID = cardID;
    }
    @Override
    public boolean equals(Object obj) {
        Person person = (Person) obj;
        if(this == person){
            return true;
        }
        if(this.cardID.equals(person.cardID)){
            return true;
        }
        return false;
    }

    @Override
    public String toString() {
        return "Person{" +
                "name='" + name + '\'' +
                ", age=" + age +
                ", cardId='" + cardID + '\'' +
                '}';
    }
}

public class School {
    private Student[] students;
    private Teacher[] teachers;

    public  void School(Student[] students, Teacher[] teachers) {
        this.students = students;
        this.teachers = teachers;
    }

    public Student[] getStudents() {
        return students;
    }

    public void setStudents(Student[] students) {
        this.students = students;
    }

    public Teacher[] getTeachers() {
        return teachers;
    }

    public void setTeachers(Teacher[] teachers) {
        this.teachers = teachers;
    }
    public  void showTeachers(){
        for (Teacher teacher : teachers) {
            System.out.println(teacher.teach());

        }
    }
    public  void showStudents(){
        for(Student student:students){
            System.out.println(student.Study());
        }
    }
}

public class Student extends Person {
    public Student(String name, int age, String cardID) {
        super(name, age, cardID);
        this.stuNo=stuNo;
        this.teacher=teacher;

    }

    private String stuNo;
    private Teacher teacher;

    public Student(String name, int age, String cardID, String stuNo, Teacher teacher) {
        super(name,age,cardID);
        this.stuNo=stuNo;
        this.teacher=teacher;
    }

    public String getStuNo() {
        return stuNo;
    }

    public void setStuNo(String stuNo) {
        this.stuNo = stuNo;
    }

    public Teacher getTeacher() {
        return teacher;
    }

    public void setTeacher(Teacher teacher) {
        this.teacher = teacher;
    }

    public String Study(){
        return this + "，\n 老师是：" +teacher;
    }
    @Override
    public String toString() {
        return super.toString() + "Student{" +
                "stuNo='" + stuNo + "}";
    }
}

package T0723;
import java.util.Arrays;

public class Teacher extends Person {

    public Teacher(String name, int age, String cardID ,String terNo) {
        super(name, age, cardID);
        this.terNo=terNo;
    }
    private String terNo;
    private Student[] students;

    public String getTerNo() {
        return terNo;
    }

    public void setTerNo(String terNo) {
        this.terNo = terNo;
    }

    public Student[] getStudents() {
        return students;
    }

    public void setStudents(Student[] students) {
        this.students = students;
    }
    public String  teach(){
        return this + "，\n" + Arrays.toString(students);
    }
    @Override
    public String toString() {
        return super.toString() + "Teacher{" +
                "terNo='" + terNo;
    }
}