希望各位大佬可以帮我解答一下。

class Person
{
public static void main(String[] args)
{ String name="abc",sex="m",age="19";
System.out.println("The name is "+name+",sex is "+sex+",age is "+age);
Student stu=new Student("2017年",28);
Teacher tea=new Teacher("cjc","abc");
System.out.println(stu);
System.out.println(tea);
} 
}
class Student extends Person
{
private String time;
private int num;
Student(String str,int number)
{
time=str;
num=number;
}
public String toString()
{
return "The time is "+time+"."+"The num is "+num+"."; 
}
}
class Teacher extends Person
{
private String title;
private String section;
Teacher(String str,String num)
{
title=str;
section=num;
}

public String toString() { return "The title " +title+".The section is " +section+".";

}
}

这个程序该怎样修改，才能在输出学生的时候输出的是它的名字，性别，年龄，学号和时间；
在输出教师的时候输出的只有名字，性别，年龄，职称和部门。

student类里面
public String toString()
{
return "名字=" + name + "，性别="+ sex +"，年龄="+age+"，学号="+num+"， 时间=" +time ;
}
教师的做法类似

你这代码结构都不太合理，我给你改了一下。但是是符合你的要求的。

 package pratice;

public class Main
{
public static void main(String[] args)
   { 
      Person person=new Person();
      Student stu=new Student("2017年",28);
      Teacher tea=new Teacher("cjc","abc");
      System.out.println(person);
      System.out.println(stu);
      System.out.println(tea);
   } 
}
class Person
{
   String name="abc",sex="m",age="19";

   public String toString()
   {
      return "The name is "+name+",sex is "+sex+",age is "+age;
   }
}
class Student extends Person
{
   private String time;
   private int num;
   Student(String str,int number)
   {
      time=str;
      num=number;
   }
   public String toString()
   {
      return super.toString()+",The time is "+time+","+"The num is "+num+"."; 
   }
}
class Teacher extends Person
{
   private String title;
   private String section;
   Teacher(String str,String num)
   {
      title=str;
      section=num;
   }
   public String toString()
   {
      return super.toString()+",The title " +title+",The section is " +section+".";
   }
}

 /* package whatever; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;


class Program
{
    public static void main (String[] args) throws java.lang.Exception
    {
        Student stu=new Student("abc", "m", "19", "2017年", 28);
        Teacher tea=new Teacher("cjc","abc");
        System.out.println(stu);
        System.out.println(tea);
    }
}

class Person
{
    public String name;
    public String sex;
    public String age;
    public String toString()
    {
        return "name=" + name + ",sex=" + sex + ",age=" + age;
    }
    public Person(String name, String sex, String age)
    {
        this.name = name; this.sex = sex; this.age = age;
    }
}
class Student extends Person
{
    public String time;
    public int num;
    public Student(String name, String sex, String age, String time, int num)
    {
        super(name, sex, age);
        this.time = time; this.num = num;
    }
    public String toString()
    {
        return "名字=" + name + "，性别=" + sex + "，年龄=" + age + "，学号=" + num + "， 时间=" + time;
    }
}
class Teacher extends Person
{
    public String title;
    public String section;
    public Teacher(String str,String num)
    {
        super("","","");
        title = str;
        section = num;
    }
    public String toString() { return "The title " +title+".The section is " +section+"."; }
}

https://ideone.com/lMT0Uy