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 import java.util.ArrayList;
 import java.util.Scanner;
 
 public class StudentSystem {
 
 static ArrayList<Student> list = new ArrayList<>();
 static{
 Student s1 = new Student("01","张三","23","q");
 Student s2 = new Student("02","李四","24","w");
 Student s3 = new Student("03","王五","25","e");
 list.add(s1);
 list.add(s2);
 list.add(s3);
 }
 
 
 private static final String ADD_STUDENT = "1";
 private static final String DELETE_STUDENT = "2";
 private static final String UPDATE_STUDENT = "3";
 private static final String QUERY_STUDENT = "4";
 private static final String EXIT = "5";
 
 public static void startStudentSystem() {
 loop: 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:查询学生");
 System.out.println("5:退出");
 System.out.println("请输入您的选择:");
 Scanner sc = new Scanner(System.in);
 String choose = sc.next();
 switch (choose) {
 case ADD_STUDENT -> addStudent(list);
 case DELETE_STUDENT -> deleteStudent(list);
 case UPDATE_STUDENT -> updateStudent(list);
 case QUERY_STUDENT -> queryStudent(list);
 case EXIT -> {
 System.out.println("退出");
 break loop;
 
 }
 default -> System.out.println("请输入已有的选项");
 }
 }
 }
 
 
 public static void addStudent(ArrayList<Student> list){
 Scanner sc = new Scanner(System.in);
 Student s = new Student();
 System.out.println("添加学生的信息");
 System.out.println("请输入id");
 while (true) {
 String sid = sc.next();
 boolean flag = contains(list,sid);
 if(flag){
 System.out.println("id已存在,添加失败,请重新录入");
 }else{
 s.setId(sid);
 break;
 }
 }
 System.out.println("请输入姓名");
 String sname = sc.next();
 s.setName(sname);
 System.out.println("请输入年龄");
 while (true) {
 String sage = sc.next();
 boolean flag = isNum(sage);
 if(flag){
 s.setAge(sage);
 break;
 }else {
 System.out.println("年龄只能为数字,请重新输入年龄。");
 }
 }
 System.out.println("请输入家庭住址");
 String saddress = sc.next();
 s.setAddress(saddress);
 list.add(s);
 System.out.println("添加成功");
 }
 
 
 public static void deleteStudent(ArrayList<Student> list){
 System.out.println("请输入要删除的学生的id");
 for(int i = 0;i<list.size();i++){
 Scanner sc = new Scanner(System.in);
 String sid = sc.next();
 boolean flag = contains(list,sid);
 if(flag){
 list.remove(getIndex(list,sid));
 System.out.println("删除成功");
 break;
 }else{
 System.out.println("该用户不存在,删除失败。");
 return;
 }
 }
 }
 
 
 public static void updateStudent(ArrayList<Student> list){
 System.out.println("请输入需要修改的学生的id");
 Scanner sc = new Scanner(System.in);
 String sid = sc.next();
 boolean flag = contains(list,sid);
 int index = getIndex(list,sid);
 if(flag){
 System.out.println("请输入需要修改的信息");
 System.out.println("修改学生姓名");
 String sname = sc.next();
 list.get(index).setName(sname);
 System.out.println("修改学生年龄");
 while (true) {
 String sage = sc.next();
 boolean flag2 = isNum(sage);
 if(flag2){
 list.get(index).setAge(sage);
 break;
 }else {
 System.out.println("年龄只能为数字,请重新输入年龄。");
 }
 }
 System.out.println("修改学生家庭住址");
 String saddress = sc.next();
 list.get(index).setAddress(saddress);
 System.out.println("修改完成");
 }else{
 System.out.println("该学生id不存在");
 }
 }
 
 
 public static void queryStudent(ArrayList<Student> list){
 System.out.println("查询学生");
 if(list.size() == 0){
 System.out.println("当前无学生信息,请添加后查询。");
 return;
 }
 System.out.println("id\t姓名\t年龄\t家庭住址");
 for (int i = 0;i<list.size();i++){
 Student stu = list.get(i);
 String sid = stu.getId();
 String sname = stu.getName();
 String sage = stu.getAge();
 String saddress = stu.getAddress();
 System.out.println(sid+"\t"+sname+"\t"+sage+"\t"+saddress);
 }
 }
 
 
 public static boolean contains(ArrayList<Student> list,String id){
 
 
 
 
 
 
 
 
 
 
 
 return getIndex(list,id) >= 0;
 }
 
 
 public static int getIndex(ArrayList<Student> list,String id) {
 
 for (int i = 0; i < list.size(); i++) {
 if (id.equals(list.get(i).getId())) {
 return i;
 }
 }
 return -1;
 }
 
 
 public static boolean isNum(String age){
 for(int i = 0;i<age.length();i++){
 char c = age.charAt(i);
 if((c>='0')&&(c<='9')){
 return true;
 }
 }
 return false;
 }
 }
 
 
 
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