java IO流 登录

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

import javax.xml.bind.annotation.adapters.XmlJavaTypeAdapter.DEFAULT;
class DD{

private static final Writer FileWriter = null;

//菜单栏
public void mm() throws IOException{
Scanner sc = new Scanner(System.in);
System.out.println("请选择功能");
System.out.println("****************");
System.out.println("(1)登录\t(2)注册");
System.out.println("****************");
int count = sc.nextInt();
switch(count){
case 1:
dd1();
break;
case 2:
dd2();
break;
default:
System.out.println("输入有误，请重新输入");
returnMain();
}
}

//返回主菜单
public void returnMain() throws IOException{
Scanner scanner = new Scanner(System.in);
System.out.println("输入-0-返回主菜单");
int a = scanner.nextInt();
if (a == 0) {
mm();
}else {
System.out.println("输入有误，请重新输入");
}
}

//登录
public void dd1() throws IOException{
Scanner scanner = new Scanner(System.in);
System.out.println("请输入账户名和密码，以-隔开");
String string = scanner.next();

//创建通道并找目标文件
FileReader fileReader = new FileReader("C:\\eclipse\\辛宇12.06\\账户密码.txt");
//缓冲
BufferedReader bufferedReader = new BufferedReader(fileReader);
String string1 = null;
boolean Y = false;
//每一次读取一行数据
while((string1 = bufferedReader.readLine()) != null){

if(string1.equals(string)){

System.out.println("登录成功");
Y = true;
}
}
if(Y == false){
System.out.println("用户不存在或输入有误");
}
//关闭资源
bufferedReader.close();
//返回主菜单
returnMain();
}

//注册
public void dd2() throws IOException {
Scanner scanner = new Scanner(System.in);
System.out.println("请输入账户名和密码，以-隔开");
String string = scanner.next();

//找目标文件
File file = new File("C:\\eclipse\\辛宇12.06\\账户密码.txt");
//创建通道
FileWriter writer = new FileWriter(file, true);
//缓冲
BufferedWriter writerw = new BufferedWriter(writer);
//写入
writerw.newLine();//换行
writerw.write(string);

//关闭资源
writerw.close();
//返回主菜单
returnMain();
}
}
public class Demo2 {

/**
* 用字符流写一个登录，注册的操作
// 1.注册的用户用和密码要写入磁盘
/*
* 存入到磁盘的数据格式。
张三 123
李四 abc

//登录是需要查找本地是否存有数据，有就登录，没有提示注册。
* @param args
* @throws IOException
*/
public static void main(String[] args) throws IOException {
// TODO Auto-generated method stub
DD d = new DD();
d.mm();
}

}