学生管理系统（基础）（练习）

需实现：
输入1：添加学生
输入2：删除学生
输入3：修改学生
输入4：查看所有学生
输入5：退出

代码：

package com.foundation;

import java.util.ArrayList;
import java.util.Scanner;

public class student_project {
    
    
    public static void main(String[] args) {
    
    
        Scanner sc = new Scanner(System.in);
        ArrayList<Student> arrayList = new ArrayList();
        while (true) {
    
    
            System.out.println("--------欢迎来到学生管理系统--------");
            System.out.println("1.添加学生");
            System.out.println("2.删除学生");
            System.out.println("3.修改学生");
            System.out.println("4.查看所有学生");
            System.out.println("5.退出");
            System.out.println("请输入选择：");
            String s1 = sc.nextLine();
            int i1 = Integer.parseInt(s1);
            switch (i1) {
    
    
                case 1:
                    if (arrayList.size() == 0) {
    
    
                        System.out.println("添加学生");
                        System.out.println("请输入学号←┘，姓名←┘，年龄←┘，居住地←┘");
                        arrayList.add(new Student(sc.nextLine(), sc.nextLine(), sc.nextLine(), sc.nextLine()));
                        System.out.println("添加成功");
                    } else {
    
    
                        System.out.println("添加学生");
                        System.out.println("请输入学号←┘，姓名←┘，年龄←┘，居住地←┘");
                        String Sid = sc.nextLine();
                        System.out.println(increase_student(Sid, arrayList));
                    }
                    break;
                case 2:
                    System.out.println("删除学生");
                    System.out.println("请输入要删除的学生学号：");
                    String s2 = sc.nextLine();
                    int count2 = 0;
                    for (int i = 0; i < arrayList.size(); i++) {
    
    
                        if (s2.equals(arrayList.get(i).getSid())) {
    
    
                            arrayList.remove(i);
                            System.out.println("删除完成");
                            count2++;
                            break;
                        }
                    }
                    if (count2!=0){
    
    
                        System.out.println("未查询到该学生");
                    }
                    break;
                case 3:
                    System.out.println("修改学生");
                    System.out.println("请输入要修改的学生学号：");
                    String s3 = sc.nextLine();
                    for (int i = 0; i < arrayList.size(); i++) {
    
    
                        if (s3.equals(arrayList.get(i).getName())) {
    
    
                            System.out.println("请输入你要修改的名字：");
                            arrayList.get(i).setName(sc.nextLine());
                            System.out.println("请输入你要修改的年龄：");
                            arrayList.get(i).setAge(sc.nextLine());
                            System.out.println("请输入你要修改的地址：");
                            arrayList.get(i).setAddress(sc.nextLine());
                            break;
                        }
                    }
                case 4:
                    System.out.println("查看所有学生");
                    if (arrayList.size() == 0) {
    
    
                        System.out.println("无学生");
                    }
                    for (int i = 0; i < arrayList.size(); i++) {
    
    
                        Student student = arrayList.get(i);
                        System.out.println("学号:" + student.getSid() + "，名字：" + student.getName() + "，年龄：" + student.getAge() + "，地址：" + student.getAddress());
                    }
                    break;
                case 5:
                    System.out.println("退出");
                    System.exit(0);
                default:
                    System.out.println("输入错误，请重新输入");
                    break;
            }
        }
    }

    public static String increase_student(String Sid, ArrayList<Student> arrayList) {
    
    
        int size;
        Scanner sc = new Scanner(System.in);
        for (int i = 0; i < arrayList.size(); i++) {
    
    
            if (arrayList.get(i).getSid().equals(Sid)) {
    
    
                System.out.println("进入");
                return "已有此学号的同学，请重新输入";
            }
        }
        arrayList.add(new Student(Sid, sc.nextLine(), sc.nextLine(), sc.nextLine()));
        return "添加成功";
    }
}