类,封装,继承,多态

Student.java

学生类:

import java.util.Objects;
import java.util.Scanner;

public class Student {
    static int age;
    static String id, subject;
    static String name = "张晗";

    //name="张晗" // 非法,因为在class类中,赋值操作语句只允许在成员函数中才可以
    //在类中不允许出现操作性的语句
    static char s = 'a';

    public static String schoolName = "烟台大学";
    //全局变量,如果具有: stu1.schoolname="鲁东大学",此时类内的全局变量也被修改,所以说会出错
    //如果不想被修改 可变为:
    public static final String SchoolName = "烟台大学";//final表示不可被修改

    public static void 上课() {
        System.out.println(name + "来上课");
    }

    public static void chifan() {
        System.out.println(name + "12点才开始吃饭");
    }

    public static void love() {
        Scanner cin = new Scanner(System.in);
        String s = cin.nextLine();
        if (Objects.equals(s, "王浩然")) System.out.println("喜欢");
        else System.out.println("不喜欢,滚");
    }

    private static String School_Name = "烟台大学";
    private String name1;

    //private 可以通过共有的函数来进行访问和修改

    public static String getSchoolName() {
        return School_Name;
    }

    public static void setSchoolName(String n) {
        School_Name = n;
    }

    public static void main(String[] args) {
        Student stu1 = new Student();
        stu1.name = "张晗";

        Student stu2 = new Student();
        stu2.name = "王浩然";
    }
}

Teacher.java

老师类:

//封装的含义:

//数据+方法一体化,可以统一放在一个类里面,类似于打包
//可以通过权限来控制某个数据是否可访问,具有数据控性
//可复用

public class Teacher {
    static String name, course;

    public static void 授课() {
        Student stu_zhanghan = new Student(); //student 叫做类,同学类
        stu_zhanghan.name = "张晗";
        stu_zhanghan.上课(); //stu是对象,类似于 张晗同学,张晗同学是在同学类中的一员
        Student stu_haoran = new Student();
        stu_haoran.name = "张晗的老公";
        stu_haoran.chifan();
    }

    public static void love() {
        Student zhanghan = new Student();
        zhanghan.love();
    }

    public static void main(String[] args) {
        Teacher.授课();
        love();
        Student stu=new Student();
        System.out.println("学校名字:"+stu.getSchoolName());
        stu.setSchoolName("鲁东大学");
        System.out.println("学校名字:"+stu.getSchoolName());
    }
}