package studentManager;
/*
    学生类
 */
public class Student {
    //学号
    private String  sid;
    //姓名
    private String name;
    //年龄
    private String age;
    //居住地
    private String address;
    //构造函数
    public Student(){}
    public Student(String sid, String name, String age, String address){
        this.sid = sid;
        this.name = name;
        this.age = age;
        this.address = address;
    }
    //Alt + insert 可以快速生成这些东西
    public String getSid() {
        return sid;
    }
    public void setSid(String sid) {
        this.sid = sid;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }
    public String getAddress() {
        return address;
    }
    public void setAddress(String address) {
        this.address = address;
    }
}

package studentManager;
import java.util.ArrayList;
import java.util.Scanner;
public class StudentManager {
    public static void main(String[] args) {
        //创建集合对象，用于存储学生数据
        ArrayList<Student> array = new ArrayList<Student>();
        while(true) {
            //用输出语句完成主界面
            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("请输入你的选择：");
            //用Scanner录入信息
            Scanner sc = new Scanner(System.in);
            String line = sc.nextLine();
            //用Switch语句完成选择
            switch(line){
                case "1":
                    //System.out.println("添加学生");
                    addStudent(array);
                    break;
                case "2":
                    //System.out.println("删除学生");
                    delectStudent(array);
                    break;
                case "3":
                    //System.out.println("修改学生");
                    updateStudent(array);
                    break;
                case "4":
                    //System.out.println("查看所有学生");
                    findAllStudent(array);
                    break;
                case "5":
                    System.out.println("谢谢使用");
                    //break;
                    System.exit(0);   //JVM退出，即Java虚拟机退出
            }
        }
    }
    //添加学生信息
    public static void addStudent(ArrayList<Student> array){
        Scanner sc = new Scanner(System.in);
        String sid;  //这里需要全局
        while(true) {
            System.out.println("请输入学生学号：");
            sid = sc.nextLine();
            boolean flag = isUsed(array, sid);
            if (flag) {
                System.out.println("你输入的学号已经被使用！请重新输入：");
            }else{
                break;
            }
        }
        System.out.println("请输入学生姓名：");
        String name = sc.nextLine();
        System.out.println("请输入学生年龄：");
        String age = sc.nextLine();
        System.out.println("请输入学生居住地：");
        String address = sc.nextLine();
        //创建学生对象
        Student s = new Student();
        s.setSid(sid);
        s.setName(name);
        s.setAge(age);
        s.setAddress(address);
        //添加到学生集合中
        array.add(s);
        //
        System.out.println("添加学生成功！");
    }
    //判断学号是否被使用
    public static boolean isUsed(ArrayList<Student> array, String sid){
        boolean flag = false;
        for(int i=0; i<array.size(); i++){
            Student s = array.get(i);
            if(s.getSid().equals(sid)){
                flag = true;
                break;
            }
        }
        return flag;
    }
    //查看学生信息
    public static void findAllStudent(ArrayList<Student> array){
        //判断集合中是否有数据
        if(array.size()==0){
            System.out.println("无信息，请先添加信息再查询！");
            return;
        }
        //显示表头信息
        // \t：tab键的意思
        System.out.println("学号\t姓名\t年龄\t\t居住地");
        //显示
        for (int i=0; i< array.size(); i++){
            Student s = array.get(i);
            System.out.println(s.getSid() + "\t" + s.getName() + "\t" + s.getAge() + "岁\t" + s.getAddress());
        }
    }
    //删除学生信息
    public static void delectStudent(ArrayList<Student> array){
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入你要删除的学生的学号：");
        String sid = sc.nextLine();
        int index = -1;
        //遍历
        for(int i=0; i< array.size(); i++){
            Student s = array.get(i);
            if (s.getSid().equals(sid)){
                index = i;
                array.remove(i);
                break;
            }
        }
        if (index==-1){
            System.out.println("该信息不存在！");
        }
        else{
            System.out.println("删除学生成功！");
        }
    }
    //修改学生信息
    public static void updateStudent(ArrayList<Student> array){
        Scanner sc = new Scanner(System.in);
        System.out.println("请输入你要修改的学生的学号：");
        String sid = sc.nextLine();
        //键盘录入要修改的学生信息
        System.out.println("请输入学生新姓名：");
        String name = sc.nextLine();
        System.out.println("请输入学生新年龄：");
        String age = sc.nextLine();
        System.out.println("请输入学生新居住地：");
        String address = sc.nextLine();
        Student s = new Student();
        s.setSid(sid);
        s.setName(name);
        s.setName(age);
        s.setAddress(address);
        //遍历信息，进行修改
        for(int i=0; i< array.size(); i++){
            Student student = array.get(i);
            if(student.getSid().equals(sid)){
                array.set(i,s);
                break;
            }
        }
        //提示修改成功
        System.out.println("修改信息成功！");
    }
}