package studentsystem;

public class student {
private String id;
private String name;
private int age;
private double score;

public student()
{
    
}
public student (String id , String name , int age , double score)
{
    this.id  = id;
    this.name = name;
    this.age = age;
    this.score = score;
}
public void setId(String id)
{
    this.id = id;
}
public String getId()
{
    return id;
}
public void setName(String name)
{
    this.name = name;
}
public String getName()
{
    return name;
}
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 studentsystem;

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

public class studentsystem {
    public static void main(String [] args) {

        //学生类集合
        ArrayList <student> list = 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.查询学生信息");
            System.out.println("5.退出");
            System.out.println("请输输入您的选择: ");

            Scanner sc  = new Scanner(System.in);
            String str = sc.next();
            switch(str) {
            case "1" -> Add(list);
            case "2" -> Delete(list);
            case "3" -> Updata(list);
            case "4" -> Find(list);
            case "5" -> {
                System.out.println("退出系统");
                return ;
            }
            default -> System.out.println("输入错误");
            }
        }
    }

    //添加
    public static void Add(ArrayList <student> list)
    {
        student s = new student();
        Scanner sc  = new Scanner(System.in);

        String id = null;
        while(true) 
        {

            System.out.println("请输入学号");
            id = sc.next();
            boolean flag = only(list , id);

            if(flag)
            {
                System.out.println("id已存在,请重新输入");
            }
            else {
                s.setId(id);
                break;
            }
        }

        System.out.println("请输入姓名");
        String name = sc.next();
        s.setName(name);
        
        System.out.println("请输入年龄");
        int age = sc.nextInt();
        s.setAge(age);
        System.out.println("请输入分数");
        double score = sc.nextDouble();
        s.setScore(score);
        //加入集合
        list.add(s);
        System.out.println("添加成功");
    }
    //删除
    public static void Delete(ArrayList <student> list)
    {
        Scanner sc = new Scanner(System.in);
        System.out.println("输入要删除的id");
         String id = sc.next();
         int index = getID(list , id) ;
         if(index >= 0)
         {
             list.remove(index);
             System.out.println("删除成功");
         }
         else {
             System.out.println("删除失败");
         }
    }
    //修改
    public static void Updata(ArrayList <student> list)
    {
        Scanner sc = new Scanner(System.in);
        System.out.println("输入修改的id");
        String id = sc.next();
        int index = getID(list , id);
        
        if(index >= 0)
        {
            student stu = list.get(index);
            
            System.out.println("请输入姓名");
            String name = sc.next();
            stu.setName(name);
            System.out.println("请输入年龄");
            int age = sc.nextInt();
            stu.setAge(age);
            System.out.println("请输入分数");
            double score = sc.nextDouble();
            stu.setScore(score);
            
            System.out.println("修改成功");
        }
        else {
            System.out.println("修改失败");
        }
    }
    //查询
    public static void Find(ArrayList <student> list)

    {
        if(list.size() == 0)
        {
            System.out.println("无学生信息");
            return ;
        }
        //输出
        System.out.println("id\t姓名\t年龄\t分数\t");
        for(int i = 0  ;i < list.size() ; i++)
        {
            student stu = list.get(i);
            System.out.println( stu.getId() + "\t" + stu.getName() + "\t" + stu.getAge() + "\t" + stu.getScore() );
                    
        }
    }

    //判断id唯一
    public static boolean only(ArrayList<student> list , String id)
    {
        for(int i = 0 ; i < list.size(); i++)
        {
            student stu = list.get(i);
            String sid = stu.getId();
            if(sid.equals(id))
            {
                return true;
            }
        }
        return false;
    }

    //获取索引
    public static int getID(ArrayList<student> list , String id)
    {
            for(int i = 0 ; i < list.size(); i++)
            {
                student stu = list.get(i);
                String sid = stu.getId();
                if(sid.equals(id))
                {
                    return i;
                }
            }
        return -1;
    }

    

}