用Java读取和写入同一个文件

Question

我想从criteria.txt文件中读取 ,以标记化并在同一文件的末尾附加标记.该程序抛出异常:No file found!我不知道我的错误在哪里.任何建议都会对我有所帮助.先感谢您!

这是我的代码:

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

public class Test
{
    private FileReader fr;
    private BufferedReader br;
    private FileWriter fw;
    private BufferedWriter bw;
    private StringTokenizer strtok;
    private String s;

    //constructor
    public Test()  
    {
        try
        {
            fw=new FileWriter("criteria.txt", true);
            bw=new BufferedWriter(fw);

            try
            {
                fr=new FileReader("criteria.txt");
                br=new BufferedReader(fr);

                while((s=br.readLine())!=null)
                {
                    strtok=new StringTokenizer(s," ");
                    while(strtok.hasMoreTokens())
                    {
                        bw.write("\n"+strtok.nextToken());
                    }
                    br.close();
                }
            }
            catch(FileNotFoundException e)
            {
                System.out.println("File was not found!");
            }
            catch(IOException e)    
            {
                System.out.println("No file found!");
            }

            bw.close();
        }
        catch(FileNotFoundException e)
        {
            System.out.println("Error1!");
        }
        catch(IOException e)    
        {
            System.out.println("Error2!");
        }
    }   

    public static void main(String[] args) 
    {
        Test t=new Test();
    }
}

Answer 1

完成读取文件后,即在while循环后,您需要关闭阅读器.目前,您在读取第一行后关闭它,IOException: Stream closed当它尝试读取第二行时会产生" ".

改成:

while((s=br.readLine())!=null)
{
    strtok=new StringTokenizer(s," ");
    while(strtok.hasMoreTokens())
    {
        bw.write("\n"+strtok.nextToken());
    }
    //br.close(); <----- move this to outside the while loop
}
br.close();