利用Java写一个学生管理系统

package bean;
public class Student {
String name;
String studentId;
String sex;
int grade;
public Student(String name，String studentId，String sex，int grade){
this.name= name;
this.studentId= studentId;
this.sex = sex;
this.grade = grade;
}
public int getGrade(){
return grade;
}
public String getName(){
return name;
}
public String getSex(){
return sex;
}
public void setGrade(int g){
this.grade = g;
}
public String getStudentId(){
return studentId;
}
}

System.out.println("***************");
  System.out.println("*欢迎来到学生管理系统 *");
  System.out.println("*1：增加学生                    *");
  System.out.println("*2：删除学生                    *");
  System.out.println("*3：修改成绩                    *");
  System.out.println("*4：查询成绩                    *");
  System.out.println("***************");
  System.out.println("您想选择的操作是：");

package test;
import java.util.*;
import bean.Student;
public class Manager {
static List<Student> StudentList = new LinkedList<Student>();
public static void main(String[] agrs){
select(StudentList);
}
private static void select(List<Student> StudentList ){
System.out.println("***************");
System.out.println("*欢迎来到学生管理系统 *");
System.out.println("*1：增加学生                    *");
System.out.println("*2：删除学生                    *");
System.out.println("*3：修改成绩                    *");
System.out.println("*4：查询成绩                    *");
System.out.println("***************");
System.out.println("您想选择的操作是：");
Scanner sc = new Scanner(System.in);
int choice = sc.nextInt();
switch(choice){
//增加学生
case 1:
System.out.print("请输入学生的姓名：");
Scanner Sname = new Scanner(System.in);
String name = Sname.nextLine();
System.out.print("请输入学生的性别：");
Scanner Ssex = new Scanner(System.in);
String sex = Ssex.nextLine();
System.out.print("请输入学生的学号：");
Scanner SId = new Scanner(System.in);
String studentId = SId.nextLine();
System.out.print("请输入学生的成绩：");
Scanner Sgrade = new Scanner(System.in);
int grade = Sgrade.nextInt();
StudentList.add(new Student(name，studentId，sex，grade));
System.out.println("添加成功！！！！！");
select(StudentList);
break;
//删除学生成绩
case 2:
System.out.print("请告诉我需要删除学生的学号：");
Scanner Sid = new Scanner(System.in);
String SstudentId = Sid.nextLine();
boolean isfindDelete = false;
for (int i = 0; i < StudentList.size(); i++) {
if(SstudentId.equals(StudentList.get(i).getStudentId())){
System.out.println("发现了该学生，正在删除...");
StudentList.remove(i);
System.out.println("删除成功!!!");
isfindDelete =true;
}
}
if(!isfindDelete){
System.out.println("抱歉，没有找到");
}
select(StudentList);
break;
//修改学生成绩
case 3:
System.out.print("请告诉我需要修改成绩学生的学号：");
Scanner GId = new Scanner(System.in);
String GstudentId = GId.nextLine();
boolean isfindChange = false;
for (int j = 0; j < StudentList.size(); j++) {
if(GstudentId.equals(StudentList.get(j).getStudentId())){
System.out.println("发现了该学生，正在修改...");
System.out.println("学生原成绩为"+StudentList.get(j).getGrade());
System.out.print("请输入修改后学生的成绩：");
Scanner Ggrade = new Scanner(System.in);
int grade2 = Ggrade.nextInt();
StudentList.get(j).setGrade(grade2);
System.out.println("修改成功!!!");
isfindChange =true;
}else{
}
}
if(!isfindChange){
System.out.println("抱歉，没有找到");
}
select(StudentList);
break;
//查看学生成绩
case 4:
System.out.print("请告诉我需要查询学生的学号：");
Scanner CId = new Scanner(System.in);
String CstudentId = CId.nextLine();
boolean isfindData = false;
for (int i = 0; i < StudentList.size(); i++) {
if(CstudentId.equals(StudentList.get(i).getStudentId())){
System.out.println("名字:"+StudentList.get(i).getName());
System.out.println("性别:"+StudentList.get(i).getSex());
System.out.println("学号:"+StudentList.get(i).getStudentId());
System.out.println("成绩:"+StudentList.get(i).getGrade());
isfindData = true;
}
}
if(!isfindData){
System.out.println("抱歉，没有找到");
}
select(StudentList);
break;
default:
System.out.println("您输入的数字有误，请重新输入：");
break;
}
}
}