定义一个Person类，含姓名、性别、年龄等字段；

定义一个Person类，含姓名、性别、年龄等字段；继承Person类设计Teacher类，增加职称、部门等字段；继承Person类设计Student类，增加学号、入学时间、专业等字段。定义各类的构造方法和toString（）方法，并分别创建对象进行测试。

源代码如下：

package pk1;
class Person{
     String name,gender;
    int age;
   
     public Person(String name,String gender,int age) {
         this.name=name;
         this.gender=gender;
         this.age=age;
     }//有参构造方法
     
     public Person(){
         this("","",0);
     }//无参构造方法
     
     public String toString() {
         return "姓名："+name+"性别："+gender+"年龄"+age;
     }
     
     public static void main(String[] args) {
         // TODO Auto-generated method stub
        Person P=new Person("李华","男",23);
        System.out.println(P);
     }
}
public class Teacher extends Person {
     String post,branch;
     public Teacher(String name,String gender,int age,String post,String branch) {
         super(name,gender,age);
         this.post=post;
         this.branch=branch;
     }
     
     public String toString() {
         return super.toString()+"职称："+post+"部门："+branch;
     }
     public static void main(String[] args) {
         // TODO Auto-generated method stub
        Teacher T=new Teacher("楚人美","女",25,"高级","戏曲");
        System.out.println(T);
     }
}
class Student extends Person{
     String num,date,major;
     
     public Student(String name,String gender,int age,String num,String date,String major) {
         super(name,gender,age);
         this.num=num;
         this.date=date;
         this.major=major;
     }
     
     public String toString() {
         return super.toString()+"学号："+num+"入学日期："+date+"专业："+major;
     }
     
     public static void main(String[] args) {
         // TODO Auto-generated method stub
        Student S=new Student("李强","男",8,"321","1988.9.1","生物");
        System.out.println(S);
     }
}