MyStudentManger_io

1,首先创建Student类 代码如下

package com.itheima;

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

    public Student() {
    }

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


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


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


    public String getAge() {
        return age;
    }
    public void setAge(String age) {
        this.age = age;
    }


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


}

测试类及方法：

package com.itheima;

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 StudentManager {
    public static void main(String[] args) throws IOException {
        String filename = "student.txt";

        while(true){
            System.out.println("--------欢迎使用学生管理系统-----Students---");
            System.out.println("1查看所有学生");
            System.out.println("2添加学生");
            System.out.println("3删除学生");
            System.out.println("4修改学生");
            System.out.println("5退出");
            Scanner sc = new Scanner(System.in);
            String choiceString = sc.nextLine();

            switch(choiceString)
            {
                case"1":
                    //查看学生
                    findAllStudent(filename);
                    break;
                case"2":
                    //添加学生
                    addStudent(filename);
                    break;
                case"3":
                    //删除学生
                    deleteStudent(filename);
                    break;
                case"4":
                    //修改学生
                    updateStudent(filename);
                    break;
                case"5":
                default:
                    System.out.println("谢谢你的使用！");
                    System.out.println("--------------------------------end---");
                    return;
            }
            for (int i = 0; i < 5; i++) {
                System.out.println();
            }
        }
    }

    public static void readData(String filename,ArrayList<Student> array) throws IOException
    {
        BufferedReader br = new BufferedReader(new FileReader(filename));

        String line;
        while((line = br.readLine())!=null)
        {
            String[] str = line.split(",");
            Student s = new Student();
            s.setId(str[0]);
            s.setName(str[1]);
            s.setAge(str[2]);
            s.setAddress(str[3]);
            array.add(s);
        }
        br.close();
    }

    public static void writerData(String filename,ArrayList<Student> array) throws IOException
    {
        BufferedWriter bw = new BufferedWriter(new FileWriter(filename));

        for (int i = 0; i < array.size(); i++) {
            StringBuilder sb = new StringBuilder();
            Student s = array.get(i);
            sb.append(s.getId()).append(",").append(s.getName()).append(",").append(s.getAge()).append(",").append(s.getAddress());
            bw.write(sb.toString());
            bw.newLine();
        }
        bw.close();
    }


    public static void findAllStudent(String filename) throws IOException
    {
        ArrayList<Student> array = new ArrayList<Student>();
        readData(filename,array);
        if(array.size()==0)
        {
            System.out.println("不好意思！目前没有学生信息可供查询，请回去从新选择！");
            return;
        }
        System.out.println("学号\t\t姓名\t年龄\t居住地");
        for (int i = 0; i < array.size(); i++) {
            Student s = array.get(i);
            System.out.println(s.getId()+"\t"+s.getName()+"\t"+s.getAge()+"\t"+s.getAddress());
        }
    }

    public static void addStudent(String filename) throws IOException
    {
        ArrayList<Student> array = new ArrayList<Student>();
        readData(filename,array);
        Scanner sc = new Scanner(System.in);
        String id;
        while(true)
        {
            boolean flag = false;
            System.out.println("请输入学生学号：");
            id = sc.nextLine();
            for (int i = 0; i < array.size(); i++) {
                Student s = array.get(i);
                if(s.getId().equals(id))
                {
                    flag = true;
                    break;
                }
            }
            if(flag)
            {
                System.out.println("您输入的学号已被占用，请重新输入：");
            }else
            {
                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);
        writerData(filename,array);
        System.out.println("添加成功！");
    }

    public static void deleteStudent(String filename) throws IOException
    {
        ArrayList<Student> array = new ArrayList<Student>();
        readData(filename,array);
        Scanner sc = new Scanner(System.in);
        while(true){
            System.out.println("请输入要删除学生的学号：");
            String id = sc.nextLine();
            int index = -1;
            for (int i = 0; i < array.size(); i++) {
                Student s = array.get(i);
                if(s.getId().equals(id))
                {
                    index = i;
                    break;
                }
            }
            if(index == -1)
            {
                System.out.println("您输入的学号有误！请重新输入：");
            }else
            {
                array.remove(index);
                writerData(filename,array);
                System.out.println("删除学生成功！");
                return;
            }
        }
    }
    public static void updateStudent(String filename) throws IOException
    {
        ArrayList<Student> array = new ArrayList<Student>();
        readData(filename,array);
        Scanner sc = new Scanner(System.in);
        while(true){
            System.out.println("请输入你要修改的学生的学号：");
            String id = sc.nextLine();
            int index = -1;
            for (int i = 0; i < array.size(); i++) {
                Student s = array.get(i);
                if(s.getId().equals(id))
                {
                    index = i;
                    break;
                }
            }
            if(index == -1)
            {
                System.out.println("您输入的学生学号不存在，请重新输入");
            }else{
                System.out.println("请输入学生新姓名：");
                String name = sc.nextLine();
                System.out.println("请输入学生新年龄：");
                String age = sc.nextLine();
                System.out.println("请输入学生新居住地：");
                String address = sc.nextLine();
                Student s = new Student();

                s.setId(id);
                s.setName(name);
                s.setAge(age);
                s.setAddress(address);

                array.set(index, s);
                writerData(filename,array);
                System.out.println("修改成功");
                return;
            }
        }
    }
}