新人第一次求救，关于BufferedWriter输出到文本的有关问题

import java.io.*;class Test{    public static void main(String agrs[]){        FileReader fr = null;        FileWriter fw = null;        BufferedReader br = null;           BufferedWriter bw = null;        try{            fr = new FileReader("C:/Users/Administrator/Desktop/运行代码/from.txt");            fw = new FileWriter("C:/Users/Administrator/Desktop/运行代码/to.txt");            br = new BufferedReader(fr);            bw = new BufferedWriter(fw);                        String line = null;            while(true){                line = br.readLine();                if(line == null){                    break;                }                System.out.println(line);    //这个有显示                bw.write(line);              //就是这里了，不知道是什么问题            }        }        catch(Exception e){            System.out.println(e);        }            finally{            try{                fw.close();                br.close();                fr.close();                   br.close();            }            catch(Exception e){                System.out.println(e);            }        }    }}