io实例

student.java

import java.io.Serializable;

public class Student implements Comparable<Student>,Serializable {
  private int id;
  private String name;
  private int age;
  
  public Student(int id, String name, int age) {
    super();
    this.id = id;
    this.name = name;
    this.age = age;
  }

  public int getId() {
    return id;
  }

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

  public String getName() {
    return name;
  }

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

  public int getAge() {
    return age;
  }

  public void setAge(int age) {
    this.age = age;
  }

  @Override
  public String toString() {
    return "Student [id=" + id + ", name=" + name + ", age=" + age + "]";
  }

  @Override
  public int compareTo(Student o) {
    return id - o.getId();
  }
  
  
}

studentManager.java

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.util.ArrayList;
import java.util.Collections;
import java.util.Scanner;

public class StudentManager {
  private ArrayList<Student> al ;
  private Scanner scanner;
  private File file;
  public StudentManager() {
    al = new ArrayList<>();
    file = new File("d://a.txt");
    scanner = new Scanner(System.in);
  }
  public void init() {//录入数据
    while(true) {
      System.out.println("请输入id:");
      int id = scanner.nextInt();
      System.out.println("请输入name:");
      String name = scanner.next();
      System.out.println("请输入age:");
      int age = scanner.nextInt();
      Student student = new Student(id, name, age);
      al.add(student);
      System.out.println("是否继续!");
      String choose = scanner.next();
      if(choose.equals("n")) {
        break;
      }
    }
  }
  //写入文件
  public void write() {
    try {
      ObjectOutputStream oos = new ObjectOutputStream(new FileOutputStream(file));
      oos.writeObject(al);
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    }
    
  }
  //读取文件
  @SuppressWarnings("unchecked")
  public void read() {
    try {
      ObjectInputStream ois = new ObjectInputStream(new FileInputStream(file));
      al = (ArrayList<Student>) ois.readObject();
    } catch (FileNotFoundException e) {
      e.printStackTrace();
    } catch (IOException e) {
      e.printStackTrace();
    } catch (ClassNotFoundException e) {
      e.printStackTrace();
    }
    
  }
  //排序
  public void sort() {
    Collections.sort(al);
  }
  //打印数据
  public void show() {
    for(Student student : al) {
      System.out.println(student);
    }
  }
  
  
}

Test.java

public class Test {

  public static void main(String[] args) {
    StudentManager manager = new StudentManager();
    manager.init();
    System.out.println("=========初始数据如下=========");
    manager.show();
    manager.write();
    System.out.println("=========排序后数据如下=========");
    manager.show();

    
  }

}