writing to a file problem

Question

I am using this code to write to a file in java. it has always worked and I am 100% sure its right. But still the file does not get written. I don't even get an error.

import java.io.BufferedWriter;   
import java.io.FileWriter;
import java.io.IOException;

public class writetofile {

    public static void main(String [] args){

        FileWriter fw;

        try {
            fw = new FileWriter("testfile.txt");

            BufferedWriter bw = new BufferedWriter(fw);

            bw.write("this is test");

            bw.write("this is test");
            bw.write("this is test");


        } catch (IOException e) {

            // TODO Auto-generated catch block
            e.printStackTrace();
        }

    }
}

Could it be some other problem?

Never be 100% sure, but 100% inquisitive ;) – Nicolas C. Aug 18 '10 at 13:50 — Nicolas C., Aug 18 '10 at 13:50

score 8 · Answer 1 · answered Aug 18 '10 at 13:31

8

You are not calling the close() method on the BufferedWriter object. That means the buffers never get flushed. Add bw.close() after your last bw.write() statements.

answered Aug 18 '10 at 13:31

Tore A.

609
3
5

thanks so much! i dont know i how missed that! super stupid! sorry! – JJunior Aug 18 '10 at 13:32
@jillika: I'm sure it has happend to every single Java programmer out there, and more than once. – Michael Borgwardt Aug 18 '10 at 13:38

score 6 · Accepted Answer · answered Aug 18 '10 at 13:30

6

try fw.flush() and fw.close()

answered Aug 18 '10 at 13:30

Sanjay Manohar

6,920
3
35
58

4

+1: ...but `bw.close()` automatically calls `bw.flush()`, so you could get away with just calling close. – Powerlord Aug 18 '10 at 13:32
thanks so much! i cant believe i dint do that :P – JJunior Aug 18 '10 at 13:33
1

:) that always happens in a hurry – LGAP Aug 18 '10 at 13:36
2

those should be bw.flush() and bw.close(), calling the fw functions wont flush the bufferedWriter – josefx Aug 18 '10 at 14:37

score 3 · Answer 3 · answered Aug 18 '10 at 13:35

You need to flush the buffer and you should close the file as well:

try {
            fw = new FileWriter("/tmp/testfile.txt");
            BufferedWriter bw = new BufferedWriter(fw);
            bw.write("this is test");
            bw.write("this is test");
            bw.write("this is test");
            bw.flush();
            fw.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

Also you should handle the IOException from the actual file writing separately from the file closing so you won't leave the file descriptor opened at the end:

    FileWriter fw = null;
    try {
        fw = new FileWriter("/tmp/testfile.txt");
        BufferedWriter bw = new BufferedWriter(fw);
        bw.write("this is test");
        bw.write("this is test");
        bw.write("this is test");
        bw.flush();
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            if (fw != null) {
                fw.close();
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

+1, the only as far who mentions closing in `finally`, the right way. Note that `flush()` is still unnecessary as `close()` implicitly does that. But that doesn't hurt. Not closing in `finally` may hurt more in exceptional cases. — BalusC, Aug 18 '10 at 13:37

score 2 · Answer 4 · answered Aug 18 '10 at 13:32

2

Make sure you call bw.close() before your method exits. If the buffer doesn't get flushed your file wont get written.

answered Aug 18 '10 at 13:32

Lazarus

41,906
4
43
54

score 1 · Answer 5 · answered Aug 18 '10 at 13:32

1

Try closing the stream with sw.close() or the data may still be cached and not actually written to disk.

answered Aug 18 '10 at 13:32

KeatsPeeks

19,126
5
52
83

writing to a file problem

5 Answers5