```java
package testStudentForIO;
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.Scanner;
public class StudentDemo {
public static void main(String[] args) throws Throwable {
ArrayList<Student> array = new ArrayList<Student>();
String fileName = "Student.txt";
while(true){
System.out.println("欢迎来到学生管理系统！");
System.out.println("1、查看现有学生");
System.out.println("2、添加学生信息");
System.out.println("3、修改学生信息");
System.out.println("4、删除学生信息");
System.out.println("5、退出系统！");
Scanner sc =new Scanner(System.in);
System.out.println("请输入您要进行的操作");
String number = sc.nextLine();
switch(number){
case "1":
findStudent(fileName);
break;
case "2":
addStudent(fileName);
break;
case "3":
changeStudent(fileName);
break;
case "4":
deleteStudent(fileName);
break;
case "5":
System.out.println("感谢您的操作！再见！");
System.exit(0);
break;
default:
System.out.println("对不起，您的输入有误，请重新输入：");
break;
}
}
}
//从文件读取到集合
public static void arrayToFile(String fileName,ArrayList<Student> array) throws IOException{
//ArrayList<Student> array = new ArrayList<Student>();
BufferedReader br = new BufferedReader(new FileReader(fileName));
String line;
while((line = br.readLine()) != null){
String[] atr = new String[1024];
atr = line.split(",");
Student s = new Student();
s.setId(atr[0]);
s.setName(atr[1]);
s.setAge(atr[2]);
s.setAddress(atr[3]);
array.add(s);
}
br.close();
}
//从集合写入到文件
public static void fileToArray(String fileName, ArrayList<Student> array) throws IOException{
BufferedWriter bw = new BufferedWriter(new FileWriter(fileName));
for (int i = 0; i < array.size(); i++) {
Student s = new Student();
s = array.get(i);
StringBuilder sb = new StringBuilder();
sb.append(s.getId()).append(",").append(s.getName()).append(",").append(s.getAge()).append(",").append(s.getAddress());
bw.write(sb.toString());
bw.newLine();
bw.flush();
}
bw.close();
}
//查看所有学生：
public static void findStudent(String fileName) throws IOException{
ArrayList<Student> array = new ArrayList<Student>();
arrayToFile(fileName,array);
if(array.size() == 0){
System.out.println("对不起，当前系统无学生信息！");
return;
}else{
System.out.println("学号,姓名,年龄,居住地");
for (int j = 0; j < array.size(); j++) {
Student s = array.get(j);
System.out.println(s.getId()+","+s.getName()+","+s.getAge()+","+s.getAddress());
}
}
}
//添加学生信息
public static void addStudent(String fileName) throws IOException{
ArrayList<Student> array = new ArrayList<Student>();
arrayToFile(fileName,array);
Scanner sc = new Scanner(System.in);
String id;
while(true){
System.out.println("请输入学生学号：");
id = sc.nextLine();
boolean flag = false;
for (int i = 0; i < array.size(); i++) {
Student s = array.get(i);
if(s.getId().equalsIgnoreCase(id)){
flag = true;
break;
}
}
if(flag){
System.out.println("对不起该学号已被占用，请重新输入！");
}
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();
Student s = new Student();
s.setId(id);
s.setName(name);
s.setAge(age);
s.setAddress(address);
array.add(s);
arrayToFile(fileName,array);
System.out.println("添加学生成功！");
}
//修改学生信息：
public static void changeStudent(String fileName) throws IOException{
ArrayList<Student> array = new ArrayList<Student>();
arrayToFile(fileName,array);
Scanner sc = new Scanner(System.in);
System.out.println("请输入您要修改的学生学号：");
String id = sc.nextLine();
while(true){
int index = -1;
for (int i = 0; i < array.size(); i++) {
Student s = new Student();
s = array.get(i);
if(s.getId().equalsIgnoreCase(id)){
index = i;
break;
}
}
if(index == -1){
System.out.println("对不起没有找到该学号");
return;
}else{
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();
Student s = new Student();
s.setId(id);
s.setName(name);
s.setAge(age);
s.setAddress(address);
array.set(index, s);
arrayToFile(fileName,array);
System.out.println("添加学生成功！");
}
}
}
//删除学生信息
public static void deleteStudent(String fileName) throws IOException{
ArrayList<Student> array = new ArrayList<Student>();
arrayToFile(fileName,array);
Scanner sc = new Scanner(System.in);
System.out.println("请输入您要修改的学生学号：");
String id = sc.nextLine();
while(true){
int index = -1;
for (int i = 0; i < array.size(); i++) {
Student s = new Student();
s = array.get(i);
if(s.getId().equalsIgnoreCase(id)){
index = i;
break;
}
}
if(index == -1){
System.out.println("对不起没有找到该学号");
return;
}else{
array.remove(index);
arrayToFile(fileName,array);
System.out.println("添加学生成功！");
}
}
}
}
```
