private static void addStudent() { Student student = new Student(); System.out.print("请输入姓名："); student.name = input.next(); System.out.print("请输入学号："); int id = input.nextInt(); boolean noCheck = true; while (noCheck) { if (studentNoList.contains(id)) {//已存在的学号 System.out.print("学号已存在，请重新输入："); id = input.nextInt(); } else { student.id = id; studentNoList.add(id); noCheck = false; } } System.out.print("请输入年龄："); student.age = input.nextInt(); student.setScoreList(new ArrayList<>()); studentList.add(student); System.out.println("---------------------添加学生成功---------------------"); menu(); }这段代码是什么意思

这段代码是 Java 语言中的一段程序，它定义了一个名为 "addStudent" 的方法，用于在程序中添加学生信息。

具体来说，它会提示用户输入学生的姓名、学号、年龄，然后创建一个 Student 类的实例，将用户输入的信息存储到该实例中。然后，程序会检查输入的学号是否已经存在，如果已经存在，则提示用户重新输入；如果不存在，则将学号添加到 studentNoList 列表中，并将 Student 实例添加到 studentList 列表中。最后，程序会显示 "添加学生成功" 的提示信息，并调用 menu() 方法，继续执行程序的其他部分。

相关问题

public static void searchStudentByCollege(Map<String,College>colleges) { Scanner scanner= new Scanner(System.in); System.out.print("请输入要查询的学院名称："); String collegeName = scanner.next(); if (colleges.containsKey(collegeName)) { College college = colleges.get(collegeName); List<ClassInfo> classInCollege = college.getAllClasses(); System.out.println("------ 学生信息 ------"); for (ClassInfo classInfo : classInCollege) { System.out.println(classInfo); List<Student> studentsInCollege = college.getStudentsByCollege(); for (Student student : studentsInCollege) { System.out.println(student); } } System.out.println("----------------------"); } else { System.out.println("未找到该学院的信息！"); } 帮我写出相关的类和构造方法 }

以下是相关的类和构造方法：

1. College类：

public class College {
private String name;
private List<ClassInfo> classes;
private Map<String, Student> students;

public College(String name, List<ClassInfo> classes, Map<String, Student> students) {
this.name = name;
this.classes = classes;
this.students = students;
}

public String getName() {
return name;
}

public List<ClassInfo> getAllClasses() {
return classes;
}

public List<Student> getStudentsByCollege() {
return new ArrayList<>(students.values());
}

public void addStudent(Student student) {
this.students.put(student.getId(), student);
}
}

2. ClassInfo类：

public class ClassInfo {
private String name;
private List<Student> students;

public ClassInfo(String name, List<Student> students) {
this.name = name;
this.students = students;
}

public String getName() {
return name;
}

public List<Student> getStudents() {
return students;
}
}

3. Student类：

public class Student {
private String id;
private String name;
private int age;

public Student(String id, String name, int age) {
this.id = id;
this.name = name;
this.age = age;
}

public String getId() {
return id;
}

public String getName() {
return name;
}

public int getAge() {
return age;
}
}

在调用该方法之前，需要先创建相应的College、ClassInfo和Student对象，并将它们组织成相应的数据结构，然后将这些对象存储在一个Map中。调用该方法时，将这个Map作为参数传入即可。

根据以下这段话写出相对应的代码文件夹中有3个类文件（.java文件），Student.java StudentUtils.java StudentManager.java 学生管理系统 1.学生实体用Student类，包含学生学号，姓名，家庭住址，电话号码 2.学生操作用StudentUtils类，包含学生信息的新增，删除，修改，查询，保存 -每次新增学生时，要将学生信息保存到文件中 -每次删除学生时，要将相应学生信息从文件中删除 -每次修改学生时，要将相应学生信息在文件中修改 -学生信息保存在StudentInfo.txt中 3.学生管理用StudentManager类 当程序运行后，出现菜单供使用者选择 新增学生信息， 删除学生信息， 修改学生信息， 查询学生信息。

以下是三个类的代码实现：

Student.java

public class Student {
    private String id;
    private String name;
    private String address;
    private String phone;

    public Student(String id, String name, String address, String phone) {
        this.id = id;
        this.name = name;
        this.address = address;
        this.phone = phone;
    }

    public String getId() {
        return id;
    }

    public String getName() {
        return name;
    }

    public String getAddress() {
        return address;
    }

    public String getPhone() {
        return phone;
    }

    public void setId(String id) {
        this.id = id;
    }

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

    public void setAddress(String address) {
        this.address = address;
    }

    public void setPhone(String phone) {
        this.phone = phone;
    }
}

StudentUtils.java

import java.io.*;
import java.util.ArrayList;

public class StudentUtils {
    private static String fileName = "StudentInfo.txt";

    public static void addStudent(Student student) {
        try {
            BufferedWriter writer = new BufferedWriter(new FileWriter(fileName, true));
            writer.write(student.getId() + "," + student.getName() + "," + student.getAddress() + "," + student.getPhone());
            writer.newLine();
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void deleteStudent(String id) {
        try {
            BufferedReader reader = new BufferedReader(new FileReader(fileName));
            ArrayList<String> lines = new ArrayList<>();
            String line;
            while ((line = reader.readLine()) != null) {
                if (!line.startsWith(id + ",")) {
                    lines.add(line);
                }
            }
            reader.close();
            BufferedWriter writer = new BufferedWriter(new FileWriter(fileName));
            for (String l : lines) {
                writer.write(l);
                writer.newLine();
            }
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static void modifyStudent(String id, Student newStudent) {
        try {
            BufferedReader reader = new BufferedReader(new FileReader(fileName));
            ArrayList<String> lines = new ArrayList<>();
            String line;
            while ((line = reader.readLine()) != null) {
                if (line.startsWith(id + ",")) {
                    line = newStudent.getId() + "," + newStudent.getName() + "," + newStudent.getAddress() + "," + newStudent.getPhone();
                }
                lines.add(line);
            }
            reader.close();
            BufferedWriter writer = new BufferedWriter(new FileWriter(fileName));
            for (String l : lines) {
                writer.write(l);
                writer.newLine();
            }
            writer.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    public static Student queryStudent(String id) {
        try {
            BufferedReader reader = new BufferedReader(new FileReader(fileName));
            String line;
            while ((line = reader.readLine()) != null) {
                if (line.startsWith(id + ",")) {
                    String[] fields = line.split(",");
                    return new Student(fields[0], fields[1], fields[2], fields[3]);
                }
            }
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return null;
    }
}

StudentManager.java

import java.util.Scanner;

public class StudentManager {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("请选择操作：");
            System.out.println("1.新增学生信息");
            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("0.退出程序");
            int choice = scanner.nextInt();
            scanner.nextLine();
            switch (choice) {
                case 1:
                    System.out.print("请输入学生学号：");
                    String id = scanner.nextLine();
                    System.out.print("请输入学生姓名：");
                    String name = scanner.nextLine();
                    System.out.print("请输入学生家庭住址：");
                    String address = scanner.nextLine();
                    System.out.print("请输入学生电话号码：");
                    String phone = scanner.nextLine();
                    Student newStudent = new Student(id, name, address, phone);
                    StudentUtils.addStudent(newStudent);
                    System.out.println("新增学生信息成功！");
                    break;
                case 2:
                    System.out.print("请输入要删除的学生学号：");
                    id = scanner.nextLine();
                    StudentUtils.deleteStudent(id);
                    System.out.println("删除学生信息成功！");
                    break;
                case 3:
                    System.out.print("请输入要修改的学生学号：");
                    id = scanner.nextLine();
                    Student student = StudentUtils.queryStudent(id);
                    if (student != null) {
                        System.out.print("请输入新的学生学号：");
                        String newId = scanner.nextLine();
                        System.out.print("请输入新的学生姓名：");
                        name = scanner.nextLine();
                        System.out.print("请输入新的学生家庭住址：");
                        address = scanner.nextLine();
                        System.out.print("请输入新的学生电话号码：");
                        phone = scanner.nextLine();
                        newStudent = new Student(newId, name, address, phone);
                        StudentUtils.modifyStudent(id, newStudent);
                        System.out.println("修改学生信息成功！");
                    } else {
                        System.out.println("学生信息不存在！");
                    }
                    break;
                case 4:
                    System.out.print("请输入要查询的学生学号：");
                    id = scanner.nextLine();
                    student = StudentUtils.queryStudent(id);
                    if (student != null) {
                        System.out.println("学号：" + student.getId());
                        System.out.println("姓名：" + student.getName());
                        System.out.println("家庭住址：" + student.getAddress());
                        System.out.println("电话号码：" + student.getPhone());
                    } else {
                        System.out.println("学生信息不存在！");
                    }
                    break;
                case 0:
                    System.out.println("程序已退出。");
                    System.exit(0);
                    break;
                default:
                    System.out.println("请输入正确的操作编号！");
                    break;
            }
        }
    }
}