面向对象的增删改查[小白篇]

面向对象的增删改查

大家好,我是一名刚入门的程序猿,从今往后我会在这里给大家分享我每天所需的知识,也用于记录我的成长.

作业题目为:定义一个数组,对其增删改查

这里以管理学生为例子

Student代码片

Student

package com.zj;

/*
* 学生类
* */
public class Student {
    private  int id;
    private  String name;
    private  int ega;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getEga() {
        return ega;
    }

    public void setEga(int ega) {
        this.ega = ega;
    }

    @Override
    public String toString() {
        return "Student{" +
                "id=" + id +
                ", name='" + name + '\'' +
                ", ega=" + ega +
                '}';
    }

    public Student(int id, String name, int ega) {
        this.id = id;
        this.name = name;
        this.ega = ega;
    }
}

StudentManager

package com.zj;

/*
* 管理学生类
* */
public class StudentManager {

    Student [] stus=new Student[30]; //固定班级的嘘学生数

     static int currCount=0;//当前的人数

    /*
    * 添加学生
    * */
    public void  add(Student student){
        stus[currCount]=student;
        currCount++;

    }

    /*
    * 查所有
    * */
public void  queryALL(){
    for (int i = 0; i <currCount ; i++) {
        System.out.println(stus[i]);
    }

}
/*
* 根据id去查询一个学生的信息
* */
public  void  byid(int id){
    for (int i = 0; i <currCount ; i++) {
        if (stus[i].getId()==id){
            System.out.println(stus[i]);
        }
    }
}
/*
* 删除
* */
public void delete(int id){
    for (int i = 0; i <currCount ; i++) {
        if (stus[i].getId()==id){
            for (int j = i; j <stus.length-1; j++) {
                if (stus[j]!=null){
                    stus[j]=stus[j+1];

                }
            }
    currCount--;
        }

    }


}
/*
* 修改学生信息 首先根据id查找到相对应的学生信息
*
* */
public  void  byid2(int id,Student student){
    for (int i = 0; i <currCount ; i++) {
     if (stus[i].getId()==id){
         stus[i]=student;

     }
    }


    }
}

StudentTest

package com.zj;

public class StudentZSGC {
    public static void main(String[] args) {
        StudentManager sm= new StudentManager();
        Student s1=new Student(1,"张三",18);
        Student s2=new Student(2,"李四",18);
        Student s3=new Student(3,"王五",18);
        Student s4=new Student(4,"杨六",18);
        sm.add(s1);
        sm.add(s2);
        sm.add(s3);
        sm.add(s4);
        sm.queryALL();//查所有
        System.out.println("================== 添加");


        sm.byid(2);

        sm.delete(2);
        System.out.println("================== 删除");
        sm.queryALL();//查所有



        System.out.println("================== 更新");
        Student student1=new Student(5,"小波",20);
        sm.byid2(1,student1);
        sm.queryALL();//查所有
    }

}
D:\jdk\bin\java.exe "-javaagent:D:\idae\IntelliJ IDEA 2020.1.1\lib\idea_rt.jar=52080:D:\idae\IntelliJ IDEA 2020.1.1\bin" -Dfile.encoding=UTF-8 -classpath D:\jdk\jre\lib\charsets.jar;D:\jdk\jre\lib\deploy.jar;D:\jdk\jre\lib\ext\access-bridge-64.jar;D:\jdk\jre\lib\ext\cldrdata.jar;D:\jdk\jre\lib\ext\dnsns.jar;D:\jdk\jre\lib\ext\jaccess.jar;D:\jdk\jre\lib\ext\jfxrt.jar;D:\jdk\jre\lib\ext\localedata.jar;D:\jdk\jre\lib\ext\nashorn.jar;D:\jdk\jre\lib\ext\sunec.jar;D:\jdk\jre\lib\ext\sunjce_provider.jar;D:\jdk\jre\lib\ext\sunmscapi.jar;D:\jdk\jre\lib\ext\sunpkcs11.jar;D:\jdk\jre\lib\ext\zipfs.jar;D:\jdk\jre\lib\javaws.jar;D:\jdk\jre\lib\jce.jar;D:\jdk\jre\lib\jfr.jar;D:\jdk\jre\lib\jfxswt.jar;D:\jdk\jre\lib\jsse.jar;D:\jdk\jre\lib\management-agent.jar;D:\jdk\jre\lib\plugin.jar;D:\jdk\jre\lib\resources.jar;D:\jdk\jre\lib\rt.jar;C:\Users\欣欣\IdeaProjects\Student\out\production\Student com.zj.StudentZSGC
Student{id=1, name='张三', ega=18}
Student{id=2, name='李四', ega=18}
Student{id=3, name='王五', ega=18}
Student{id=4, name='杨六', ega=18}
================== 添加
Student{id=2, name='李四', ega=18}
================== 删除
Student{id=1, name='张三', ega=18}
Student{id=3, name='王五', ega=18}
Student{id=4, name='杨六', ega=18}
================== 更新
Student{id=5, name='小波', ega=20}
Student{id=3, name='王五', ega=18}
Student{id=4, name='杨六', ega=18}

Process finished with exit code 0

这些就是全部的代码, 我会定期更新一些所学的JAVA知识,欢迎大家多多指导;

本文地址：https://blog.csdn.net/qq_44303639/article/details/107347388