用Java定义一个学生类Student, 有属性name，no，age，sex等 * 2. 定义一个 学生管理类StudentManger , 用于存储全部学生 对象 的信息 * 它的行为有: * -添加学生：通过键盘录入学生信息，添加到集合中。 * -删除学生：通过键盘录入要删除学生的学号，将该学生对象从集合中删除。 * -修改学生：通过键盘录入要修改学生的学号，将该学生对象其他信息进行修改。 * -查看学生：将集合中的学生对象信息进行展示。 */

Student类的定义：

public class Student {
    private String name;
    private String no;
    private int age;
    private String sex;

    public Student(String name, String no, int age, String sex) {
        this.name = name;
        this.no = no;
        this.age = age;
        this.sex = sex;
    }

    // getter and setter methods
}

StudentManager类的定义：

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

public class StudentManager {
    private ArrayList<Student> students = new ArrayList<>();

    public void addStudent() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入学生姓名：");
        String name = scanner.nextLine();
        System.out.println("请输入学生学号：");
        String no = scanner.nextLine();
        System.out.println("请输入学生年龄：");
        int age = scanner.nextInt();
        scanner.nextLine(); // 读取换行符
        System.out.println("请输入学生性别：");
        String sex = scanner.nextLine();
        Student student = new Student(name, no, age, sex);
        students.add(student);
        System.out.println("添加成功！");
    }

    public void removeStudent() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入要删除学生的学号：");
        String no = scanner.nextLine();
        for (int i = 0; i < students.size(); i++) {
            if (students.get(i).getNo().equals(no)) {
                students.remove(i);
                System.out.println("删除成功！");
                return;
            }
        }
        System.out.println("找不到该学生！");
    }

    public void modifyStudent() {
        Scanner scanner = new Scanner(System.in);
        System.out.println("请输入要修改学生的学号：");
        String no = scanner.nextLine();
        for (int i = 0; i < students.size(); i++) {
            if (students.get(i).getNo().equals(no)) {
                System.out.println("请输入新的学生姓名：");
                String name = scanner.nextLine();
                System.out.println("请输入新的学生年龄：");
                int age = scanner.nextInt();
                scanner.nextLine(); // 读取换行符
                System.out.println("请输入新的学生性别：");
                String sex = scanner.nextLine();
                students.get(i).setName(name);
                students.get(i).setAge(age);
                students.get(i).setSex(sex);
                System.out.println("修改成功！");
                return;
            }
        }
        System.out.println("找不到该学生！");
    }

    public void showStudents() {
        System.out.println("所有学生信息如下：");
        for (Student student : students) {
            System.out.println(student.getName() + "\t" + student.getNo() + "\t" + student.getAge() + "\t" + student.getSex());
        }
    }
}

使用示例：

public class Main {
    public static void main(String[] args) {
        StudentManager manager = new StudentManager();
        Scanner scanner = new Scanner(System.in);
        while (true) {
            System.out.println("请输入数字选择操作：");
            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. 查看学生");
            System.out.println("0. 退出程序");
            int choice = scanner.nextInt();
            scanner.nextLine(); // 读取换行符
            switch (choice) {
                case 0:
                    System.exit(0);
                    break;
                case 1:
                    manager.addStudent();
                    break;
                case 2:
                    manager.removeStudent();
                    break;
                case 3:
                    manager.modifyStudent();
                    break;
                case 4:
                    manager.showStudents();
                    break;
                default:
                    System.out.println("请输入正确的数字！");
                    break;
            }
        }
    }
}