菜鸟学Java 封装、实体类

川长思鸟来 2023-10-13 09:23 69阅读 0赞

![在这里插入图片描述][cb40a79297db41a08f117c25dd9560d5.png]

package it.heima.loop1;
    
    public class score {
        
        private  double score;
    
        public  void setScore(double score){
        
            if (score <= 100 && score >= 0){
        
                this.score = score;
            }else{
        
                System.out.println("输入错误");
            }
    
        }
    
        public double getScore(){
        
            return score;
        }
    
        public void print(){
        
            System.out.println(score>60? "成绩及格":"不及格");
        }
    }

以及

package it.heima.loop1;
    
    public class test {
        
        public static void main(String[] args) {
        
            score t = new score();
            t.setScore(-12);
            double result = t.getScore();
            System.out.println(result);
    
            t.print();
    
        }
    }

输出

输入错误
    0.0
    不及格

### 实体类 ###

主打一个保存数据  
![在这里插入图片描述][9dfe704a52c849918b1d9d14414a8214.png]  
快捷方式：`右键-生成`

![在这里插入图片描述][cfeefb99f39440e884839d405811c4af.png]

package it.heima.loop2;
    
    public class student {
        
        private int age;
        private double score;
    
        public student() {
        
        }
    
        public student(int age, double score) {
        
            this.age = age;
            this.score = score;
        }
    
        public int getAge() {
        
            return age;
        }
    
        public void setAge(int age) {
        
            this.age = age;
        }
    
        public double getScore() {
        
            return score;
        }
    
        public void setScore(double score) {
        
            this.score = score;
        }
    }

package it.heima.loop2;
    
    public class oprate {
        
        public student studenta;
        public void studentoprate(student studenta){
        
            this.studenta = studenta;
        }
    
        public  void print(){
        
            if (studenta.getScore()>= 60){
        
                System.out.println(studenta.getAge()+"哈哈");
            }else{
        
                System.out.println(studenta.getAge()+"嘿嘿");
            }
        }
    }

package it.heima.loop2;
    
    public class test {
        
        public static void main(String[] args) {
        
            student s1 = new student();
            s1.setAge(18);
            s1.setScore(21);
            System.out.println(s1.getAge());
            System.out.println(s1.getScore());
    
            student s2 = new student();
            s2.setAge(118);
            s2.setScore(221);
            System.out.println(s2.getAge());
            System.out.println(s2.getScore());
    
            oprate op = new oprate();
            op.studentoprate(s1);
            op.print();
    
        }
    }

输出结果

18
    21.0
    118
    221.0
    18嘿嘿

> 1.什么是实体类?有啥特点?

成员变量必须私有，且要为他们提供get、set方法;必须有无参数构造器。仅仅只是一个用来保存数据的java类，可以用它创建对象，保存某个事物的数据。

> 2.实体类有啥应用场景?

实体类对应的是软件开发里现在比较流行的开发方式，数据和数据的业务处理相分离。

[cb40a79297db41a08f117c25dd9560d5.png]: https://img-blog.csdnimg.cn/cb40a79297db41a08f117c25dd9560d5.png
[9dfe704a52c849918b1d9d14414a8214.png]: https://img-blog.csdnimg.cn/9dfe704a52c849918b1d9d14414a8214.png
[cfeefb99f39440e884839d405811c4af.png]: https://img-blog.csdnimg.cn/cfeefb99f39440e884839d405811c4af.png