How to delete a line from text file in Java

Question

I am creating one application in Java swing api. I am using txt file as my database to store,update etc. I completed storing procedure successfully. But I cant update .If I click update button on my application the data in file could not be replaced. can you please tel me how to replace a data in file?

Thanks in advance...

import java.io.*;

public class test {

    public static void main(String args[]) {
        try {
            String data = null;
            File file = new File("student.txt", true);
            FileReader fr = new FileReader(file);
            BufferedReader br = new BufferedReader(fr);
            while ((data = br.readLine()) != null) {
                String[] de = data.split(" ");
                if (de[0].equals("vimal")) {
                    data.trim();
                }
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

have you red the [faq](http://stackoverflow.com/faq)? also, if posting code, please post an [SSCCE](http://sscce.org/) — linski, Feb 01 '13 at 12:32
You'll probably realize that by only telling _I can't update_, or _data in the file could not be replaced_, it's exceedingly unlikely that someone can reasonably answer this question. Can you please provide more details? — Xavi López, Feb 01 '13 at 12:33
As `java.io.File` has no such constructor; this example fails to compile. — trashgod, Feb 01 '13 at 12:41
What's the swing tag for? I can't see a single Swing-UI element in your code. — Guillaume Polet, Feb 01 '13 at 12:48
See this response , might help you [Java - delete line from text file by overwriting while reading it][1] [1]: http://stackoverflow.com/a/6477893/945317 — SomeCode.NET, Feb 01 '13 at 13:19

score 0 · Answer 1 · edited Feb 01 '13 at 13:57

0

you need to close your buffered reader after all and in your fileReader need an "True"

 import java.io.*;
 public class test {
   public static void main(String args[]) {
    try {
      String data= null;
      File file=new File("student.txt");
      FileReader fr =new FileReader(file,true);
      BufferedReader br = new BufferedReader(fr);
      while((data=br.readLine())!= null) {
        String[] de = data.split(" "); 
        if(de[0].equals("vimal")) {
           data.trim();
        }
      }
    } catch (IOException e) {
        e.printStackTrace();
    }
    br.close()
  }
 }

edited Feb 01 '13 at 13:57

Amarnath

8,736
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answered Feb 01 '13 at 12:36

M.Kreusburg

19
6

3

Pleas format your code; `java.io.File` has no such constructor. – trashgod Feb 01 '13 at 12:39
3

`String` literals must be quoted, and the example remains almost unreadable. – trashgod Feb 01 '13 at 12:48
1

If you do the effort of posting an answer to indicate the reader must be closed, at least put it in a `finally` block – Robin Feb 01 '13 at 14:35

How to delete a line from text file in Java

1 Answers1