封装与私有关键字

package ren.redface.demo;

/*
 * 学生类
 */
public class Student {
    private String name;
    private int age;
    
    public void setName(String n) {
        name = n;
    }
    
    public String getName() {
        return name;
    }
    
    public void setAge(int a) {
        age = a;
    }
    
    public int getAge() {
        return age;
    }

/*
 * 学生类的测试类
 */
    public static void main(String[] args) {
        //创建对象
        Student s = new Student();
        System.out.println(s.getName()+"---"+s.getAge());
        
        s.setName("林青霞");
        s.setAge(28);
        System.out.println(s.getName()+"---"+s.getAge());
    }
}

或者建两个class

package ren.redface.demo;

/*
 * 学生类
 */
public class Student {
    private String name;
    private int age;
    
    public void setName(String n) {
        name = n;
    }
    
    public String getName() {
        return name;
    }
    
    public void setAge(int a) {
        age = a;
    }
    
    public int getAge() {
        return age;
    }
}

package ren.redface.demo;

/*
 * 学生类的测试类
 */
public class StudentDemo {
    public static void main(String[] args) {
        //创建对象
        Student s = new Student();
        System.out.println(s.getName()+"---"+s.getAge());
        
        s.setName("林青霞");
        s.setAge(28);
        System.out.println(s.getName()+"---"+s.getAge());
    }
}