Java I/O 和collection 写了很长时间才写好的程序，做个纪念

import java.io.*;
import java.util.*;

public class Test6_Map {
	public static void main(String[] args) {
		MyMapStu mms = new MyMapStu(new File("exp.txt"));
		System.out.println("请输入要查找内容的学号！");
		Scanner sc = new Scanner(System.in);
		long sno = sc.nextLong();
		Student stu2 = new Student(sno, " ");
		if(mms.containsKey(stu2)) {
			System.out.println("The name is "+mms.get(stu2.getNo()));
			
		} else {
			System.out.println("No such person!");
		}
	}
}

class Student {   //简单定义学生类
	private Long sno;
	private String sname;
	
  public Student() {
  }
  public Student(Long sno, String sname) {
  	this.sno = sno;
  	this.sname = sname;
  }
  
  public Long getNo() {
  	return sno;
  }
  public String getName() {
  	return sname;
  }
  
}

class MyMapStu { //定义此类主要是为了与文件连接，从中把数据读到map中。
	Map<Long, String> map;
	
	public MyMapStu(File stuInfo) {
		if(!stuInfo.exists()) {
			try {
				stuInfo.createNewFile();
				System.out.println("请建一个拥有30名学生学生信息表！");
				BufferedWriter fos = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(stuInfo)));
				byte[] bytes = new byte[40];
				for(int i=0; i<30; i++) {
					BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
					String str = new String();
					str = br.readLine();
					fos.write(str, 0, str.length());
					fos.newLine();		
				}
				fos.close();
		  } catch(IOException e) {
		  	e.printStackTrace();
		  }
		}
		
		try {
			map = new HashMap<Long, String>();
			BufferedReader fis = new BufferedReader(new InputStreamReader(new FileInputStream(stuInfo)));
			String stmp;
			while((stmp = fis.readLine())!=null) {
				System.out.println(stmp);
				String[] sArray = stmp.split(" "); 
			  Student stu = new Student(Long.parseLong(sArray[0]), sArray[1]);
			  map.put(stu.getNo(), stu.getName());	 
			}
			fis.close();
			System.out.println(map);
		} catch(IOException e) {
			e.printStackTrace();
		}
	}
	
	public boolean containsKey(Student stu) {
		if(map.containsKey(stu.getNo())) {
			return true;
		} else {
			return false;
		}
	}
	
	public String get(Long sno) {
		if(map.containsKey(sno)) {
			return map.get(sno);
		} else {
			return null;
		}		
	} 
	
}