非常简约学生管理系统——HashSet进行编写

package com.xt.homework;

public class Student {
    
    private String id;
    private String name;

    

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

    public Student(String id) {
        this.id=id;
    }

    public String getId() {
        return id;
    }

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

    
    
    public String getName() {
        return name;
    }

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

    @Override
    public int hashCode() {
        return this.id.hashCode();
    }

    @Override
    public boolean equals(Object obj) {
        if(obj instanceof Student&& this instanceof Student)
            return (this.id.equals(((Student)obj).id));
        return false;
    }

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

package com.xt.homework;

import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class Test {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        Set<Student> student = new HashSet<>();
        while(true){
            System.out.println("欢迎登陆学生管理系统：\n1:添加学生信息；\n2:删除学生信息；\n3:修改学生信息；\n4:查询学生信息；");
            int option = scanner.nextInt();
            switch (option) {
                case 1:{
                    System.out.println("------------添加学生-------------");
                    System.out.println("请输入学生的学号：");
                    String id=scanner.next();
                    System.out.println("请输入学生的姓名：");
                    String name=scanner.next();
                    student.add(new Student(id,name));
                    System.out.println("添加成功");
                    break;
                }
                case 2:{
                    System.out.println("************删除学生****************");
                    System.out.println("请输入删除学生的学号：");
                    String deleteID=scanner.next();
                    boolean result = student.remove(new Student(deleteID));
                    if (result) {
                        System.out.println("删除成功");
                    } else {
                        System.out.println("没有id为"+deleteID+"的学生！");
                    }
                    break;
                }
                case 3:{
                    System.out.println("################修改学生信息####################");
                    System.out.println("请输入需要修改的id号：");
                    String updateID = scanner.next();
                    System.out.println("请输入新的姓名：");
                    String name=scanner.next();
                    boolean tag = false;
                    for (Student student2 : student) {
                        if(student2.getId().equals(updateID)) {
                            student.remove(student2);
                            student.add(new Student(updateID,name));
                            System.out.println("修改成功");
                            tag=true;
                            break;
                        }
                    }
                    if(!tag) {
                        System.out.println("修改失败！！");
                    }
                    break;
                }
                case 4:{
                    System.out.println("@@@@@@@@@@@@@@@@@@查询学生信息@@@@@@@@@@@@@@@@@@@@@@@");
                    System.out.println("请输入需要查询学生的id：");
                    String selectID = scanner.next();
                    boolean tag = false;
                    for (Student stu : student) {
                        if(stu.getId().equals(selectID)) {
                            System.out.println(stu);
                            tag=true;
                            System.out.println("查询成功！！！");
                            break;
                        }
                    }
                    if(!tag) {
                        System.out.println("没有id为"+selectID+"的学生！");
                    }
                    break;
                }
                default:
                    System.out.println("没有该操作");;
            }
        }
    }
}