Java继承的实现与继承限制分析

public class ExtendsDemo01 {
  static class Person{
    private int age;
    private String name;
    public int getAge() {
      return age;
    }
    public void setAge(int age) {
      this.age = age;
    }
    public String getName() {
      return name;
    }
    public void setName(String name) {
      this.name = name;
    }
    public void tell(){
      System.out.println("姓名: "+getName()+" 年龄:"+getAge());
    }
  }
  static class Student extends Person{
    private int score;
    public int getScore() {
      return score;
    }
    public void setScore(int score) {
      this.score = score;
    }
    public void say(){
      System.out.println("成绩:"+getScore());
    }
  }
  public static void main(String [] args){
    Student s=new Student();
    s.setAge(20);
    s.setName("张三");
    s.setScore(100);
    s.tell();
    s.say();
  }
}

public class ExtendsDemo02 {
  static class People{
    private int age;
    public int getAge() {
      return age;
    }
    public void setAge(int age) {
      this.age = age;
    }
  }
  static class Worker extends People{
    public void tell(){
      System.out.println(getAge());
    }
  }
  static class PetWorker extends Worker{
  }
  public static void main(String [] args){
    Worker worker=new Worker();
    worker.setAge(100);
    worker.tell();
  }
}