Java 抽象

关键字：abstract

public abstract class Person {    //用abstract关键字将Person类定义为抽象类
    protected String name;
    protected int age;
    public Person(String name, int age) {
        this.name = name;
        this.age = age;
    }
    protected abstract void greet();    //抽象函数
}

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

    @Override
    public void greet() {
        System.out.printf("Hey, here's %s!", name);
    }
}

public class Lab{
    public static void main(String[] args) {
        Student stu = new Student("Johnny", 22);
        stu.greet();
    }
}