java 封装和隐藏 权限修饰符

问题的引入

封装性的体现

package lesson.l11_oop2;


public class Person {
    private int age;

    public void setAge(int age) {

        if (age >= 0 && age <= 130) {
            this.age = age;
        } else {
//            this.age = 0;
            throw new RuntimeException("传入的数据非法");
        }
    }

    public int getAge() {
        return this.age;
    }
}

class PersonTest {
    public static void main(String[] args) {
        Person person = new Person();
        person.setAge(-9);
        System.out.println(person.getAge());
    }
}