为什么checkID()函数在这里使用的是bufferReader而不是bufferWriter?

这是一个航班预订系统,所以这是旅客的等级。在这个类中,如果用户还没有帐户,我们有注册的功能。然而,在本例中,它使用缓冲读取器检查仍在注册的旅行者的id。难道不应该使用缓冲区写入程序将旅行者的ID写入CSV文件吗?请纠正我并详细解释。谢谢

public  void signUp(String filepath) throws IOException {
    int check = 0;
    String path = filepath;
    FileWriter fw = new FileWriter(path, true);
    BufferedWriter br = new BufferedWriter(fw);
    PrintWriter pw = new PrintWriter(br);
    
    Scanner i = new Scanner(System.in);
    
    System.out.println("Enter your name");
    String name = i.next();
    
    System.out.println("Enter your password");
    String password = i.next();

    int travellerID = (int)(Math.random()*90000 + 100000);

    check = checkID(travellerID);
    while(check==1) {
        int temp = (int)(Math.random()*90000 + 100000);
        travellerID = temp;
        check = checkID(travellerID);
    }
    
    pw.println(name+","+password+","+travellerID);

    pw.println(name+","+password);
    pw.flush();
    pw.close();

    System.out.println("Congratulations, you have signed up as a passenger!");
    System.out.printf("Your ID is %d \n", travellerID);
    
}
public int checkID(int ID) throws IOException {
    String passengerID = String.valueOf(ID);
    int check = 0;
    BufferedReader br = new BufferedReader(new FileReader("publishedFlights.csv"));
    String line;
    while((line=br.readLine())!=null) {
        String[] values = line.split(",");
        if(values[2].contentEquals(passengerID)) {
            check = 1;
        }
    }
    return check;
}