用Java实现简单的学生管理系统

目的：实现一个具有以下功能的学生管理系统

1、添加学生信息
2、删除学生信息
3、修改学生信息
4、查询指定学生信息
5、查询所有学生信息
（主要采用的是map集合）

先来看看main方法的整体架构:

static Scanner sc = new Scanner(System.in);
static Map students = new HashMap<>();

public static void main(String[] args) {
        print();
        boolean flag = true;
        while (flag) {
            int n = showMenu();
            switch (n) {
                case 1:
                    addData();
                    break;
                case 2:
                    deleteData();
                    break;
                case 3:
                    updateData();
                    break;
                case 4:
                    selectOneData();
                    break;
                case 5:
                    selectAllData();
                    break;
                default:
                    flag = false;
                    break;
            }
        }

再者是其中方法的细节内容

0、程序标题及菜单界面

public static void print() {
        System.out.println("***********************");
        System.out.println("*                     *");
        System.out.println("*    学生信息管理系统    *");
        System.out.println("*                     *");
        System.out.println("***********************");
    }
public static int showMenu() {
        System.out.println("***********************");
        System.out.println("1、添加学生信息");
        System.out.println("2、删除学生信息");
        System.out.println("3、修改学生信息");
        System.out.println("4、查询指定学生信息");
        System.out.println("5、查询所有学生信息");
        System.out.println("6、退出程序");
        System.out.println("***********************");
        System.out.print("请选择你的输入（只能输入1、2、3、4、5、6）:");
        return sc.nextInt();
    }

1、添加学生信息

public static void addData() {
        System.out.print("请输入学生id:");
        int id_add = sc.nextInt();
        while (true){
            if (students.containsKey(id_add)){
                System.out.print("该学号已经存在，请更换学号输入:");
                id_add = sc.nextInt();
            } else {
                break;
            }
        }
        System.out.print("请输入学生姓名:");
        String name_add = sc.next();
        System.out.print("请输入学生性别:");
        String sex_add = sc.next();
        System.out.print("请输入学生成绩:");
        double score_add = sc.nextDouble();
        students.put(id_add, new Student(name_add, sex_add, score_add));
    }

2、删除学生信息

public static void deleteData() {
        System.out.print("请输入要删除的学生学号");
        while (true){
            int id_delete = sc.nextInt();
            if (students.containsKey(id_delete)){
                students.remove(id_delete);
                System.out.println("学号为"+id_delete+"的学生已经被删除!");
                break;
            } else {
                System.out.print("不存在该学生信息，请再次输入学号:");
            }
        }
    }

3、修改学生信息

public static void updateData() {
        System.out.print("请输入要更改的学生学号:");
        while (true){
            int id_update= sc.nextInt();
            if (students.containsKey(id_update)){
                System.out.print("请输入学生姓名:");
                String name_update = sc.next();
                System.out.print("请输入学生性别:");
                String sex_update = sc.next();
                System.out.print("请输入学生成绩:");
                double score_update = sc.nextDouble();
                students.put(id_update, new Student(name_update, sex_update, score_update));
                break;
            } else {
                System.out.print("不存在该学生信息，请再次输入学号:");
            }
        }
    }

4、查询指定学生信息

public static void selectOneData() {
        System.out.print("请输入要查询的学生学号:");
        while (true){
            int id_select = sc.nextInt();
            if (students.containsKey(id_select)){
                System.out.println("--------------------");
                System.out.println("姓名:" + students.get(id_select).getName());
                System.out.println("性别:" + students.get(id_select).getSex());
                System.out.println("成绩:" + students.get(id_select).getScore());
                System.out.println("--------------------");
                break;
            } else {
                System.out.print("不存在该学生信息，请再次输入学号:");
            }
        }
    }

5、查询所有学生信息

public static void selectAllData() {
        for (Map.Entry entry : students.entrySet()) {
            System.out.println("--------------------");
            System.out.println("学号:" + entry.getKey());
            System.out.println("姓名:" + entry.getValue().getName());
            System.out.println("性别:" + entry.getValue().getSex());
            System.out.println("成绩:" + entry.getValue().getScore());
            System.out.println("--------------------");
        }
    }

最后再来展示一下Student类

public class Student {
    private String name;
    private String sex;
    private double score;

    public Student() {
    }

    public Student(String name, String sex, double score) {
        this.name = name;
        this.sex = sex;
        this.score = score;
    }

    public String getName() {
        return name;
    }

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

    public String getSex() {
        return sex;
    }

    public void setSex(String sex) {
        this.sex = sex;
    }

    public double getScore() {
        return score;
    }

    public void setScore(double score) {
        this.score = score;
    }

    @Override
    public String toString() {
        return "Student{" +
                "name='" + name + ''' +
                ", sex='" + sex + ''' +
                ", score=" + score +
                '}';
    }
}