java定义一个Person抽象类，包含姓名和年龄两个属性，以及一 个抽象方法work()。定义Employee类继承Person类，并实 现自己特有的work()方法，定义Student类继承Person类， 并实现自己特有的study()方法的测试类

下面是Java代码实现：

abstract class Person {
    private String name;
    private int age;

    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }

    public String getName() {
        return name;
    }

    public int getAge() {
        return age;
    }

    public abstract void work();
}

class Employee extends Person {
    public Employee(String name, int age) {
        super(name, age);
    }

    @Override
    public void work() {
        System.out.println("I am an employee and I work in the company.");
    }
}

class Student extends Person {
    public Student(String name, int age) {
        super(name, age);
    }

    @Override
    public void work() {
        System.out.println("I am a student and I study in the school.");
    }

    public void study() {
        System.out.println("I am a student and I am studying now.");
    }
}

public class Test {
    public static void main(String[] args) {
        Person p1 = new Employee("Tom", 30);
        Person p2 = new Student("Jerry", 20);

        System.out.println(p1.getName() + ", " + p1.getAge());
        p1.work();

        System.out.println(p2.getName() + ", " + p2.getAge());
        p2.work();
        ((Student) p2).study(); // 强制类型转换，调用子类特有的方法
    }
}

运行结果：

Tom, 30
I am an employee and I work in the company.
Jerry, 20
I am a student and I study in the school.
I am a student and I am studying now.