Inheritance of Java classes: simple inheritance of Java and the difference between single inheritance and multi inheritance

Simple inheritance

class class_name extends extend_class
{
    //类的主体
}

public class Student extends Person{}

Example 1

public class People
{
    public String name;    //姓名
    public int age;    //年龄
    public String sex;    //性别
    public String sn;    //身份证号
    public People(String name,int age,String sex,String sn)
    {
        this.name=name;
        this.age=age;
        this.sex=sex;
        this.sn=sn;
    }
    public String toString()
    {
        return"姓名："+name+"\n年龄："+age+"\n性别："+sex+"\n身份证号："+sn;
    }
}

public class Student extends People
{
    private String stuNo;    //学号
    private String department;    //所学专业
    public Student(String name,String sn,String stuno,String department)
    {
        super(name,age,sex,sn);    //调用父类中的构造方法
        this.stuNo=stuno;
        this.department=department;
    }
    public String toString()
    {
        return"姓名："+name+"\n年龄："+age+"\n性别："+sex+"\n身份证号："+sn+"\n学号："+stuNo+"\n所学专业："+department;
    }
}

public class Teacher extends People
{
    private int tYear;    //教龄
    private String tDept;    //所教专业
    public Teacher(String name,int tYear,String tDept)
    {
        super(name,sn);    //调用父类中的构造方法
        this.tYear=tYear;
        this.tDept=tDept;
    }
    public String toString()
    {
        return"姓名："+name+"\n年龄："+age+"\n性别:"+sex+"\n身份证号："+sn+"\n教龄："+tYear+"\n所教专业："+tDept;
    }
}

public class PeopleTest
{
    public static void main(String[] args)
    {
        //创建Student类对象
        People stuPeople=new Student("王丽丽",23,"女","410521198902145589","00001","计算机应用与技术");
        System.out.println("----------------学生信息---------------------");
        System.out.println(stuPeople);

        //创建Teacher类对象
        People teaPeople=new Teacher("张文",30,"男","410521198203128847",5,"计算机应用与技术");
        System.out.println("----------------教师信息----------------------");
        System.out.println(teaPeople);
    }
}

----------------学生信息---------------------
姓名：王丽丽
年龄：23
性别：女
身份证号：410521198902145589
学号：00001
所学专业：计算机应用与技术
----------------教师信息----------------------
姓名：张文
年龄：30
性别:男
身份证号：410521198203128847
教龄：5
所教专业：计算机应用与技术

Single inheritance

class Student extends Person,Person1,Person2{…}
class Student extends Person,extends Person1,extends Person2{…}