private修饰后，当前变量只能在当前的内中才能操作

// 定义一个学生类
class Student{
    String name;
    private int score;
    public void setScore(int s){
        if (s>=0 && s<=100){
            score = s;
        }else {
            System.out.println("成绩不符合规范！");
        }
    }
    public void show(){
        System.out.println("姓名："+name);
        System.out.println("分数："+score);
    }
}
public class StudentDemo1 {
    public static void main(String[] args) {
        Student s1 = new Student();
        //为S1对象的成员变量
        s1.name = "张飞";
//        s1.score = -30;
        s1.setScore(90);
        s1.show();
    }
}

private 设置为私有属性

java中用this修饰的变量为成员变量

// 定义一个学生类
class Student{
    String name;
    private int score;
    public void setScore(int score){
        if (score>=0 && score<=100){
            this.score = score;
            System.out.println(this);
        }else {
            System.out.println("成绩不符合规范！");
        }
    }
    public void show(){
        System.out.println("姓名："+name);
        System.out.println("分数："+score);
    }
}
public class StudentDemo1 {
    public static void main(String[] args) {
        Student s1 = new Student();
        //为S1对象的成员变量
        s1.name = "张飞";
//        s1.score = -30;
        s1.setScore(90);
        s1.show();
    }
}