import *;
public class FileOperation{
 public static void main(String args[]){
 BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
 File myfile=new File("Line.txt");
 String s;
 try{
 BufferedWriter bw=new BufferedWriter(new FileWriter(myfile));
 while(true){  
  System.out.println("输入字符串：");
  s=br.readLine();
  if(s.length()==0) break;
  bw.write(s);
  bw.newLine();
  }
  bw.close();
  }
  catch(IOException e){}  
  try{
  BufferedReader brF=new BufferedReader(new FileReader(myfile));
  while(true){
  s=brF.readLine();
  if(s.length()==0) break;
  }  }
  catch(IOException e){}                                                                     
 }
}
求教大神们此处该如何改，谢谢呀！！

import *;
public class FileOperation{
public static void main(String args[]){
BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
File myfile=new File("Line.txt");
String s;
try{
BufferedWriter bw=new BufferedWriter(new FileWriter(myfile));
while(true){  
  System.out.println("输入字符串：");
  s=br.readLine();
  if(s.length()==0) break;
  bw.write(s);
  bw.newLine();
  }
  bw.close();
  }
  catch(IOException e){}  
  try{
  BufferedReader brF=new BufferedReader(new FileReader(myfile));
  while(true){
  s=brF.readLine();
  if(s==null) break;
  System.out.println(s);
  }
  brF.close();
  }
  catch(IOException e){}                                                                      
}
}

主要是读文件时文件结束判断错误，应该是 if(s==null) break;

非常感谢，按你的方法确实对的，可是我还是不明白为什么用if(s.length()==0)来判断结束就不行？你能讲讲吗？

怎么没人回了哦？人气不旺呀

路过