Java BufferedWriter can't write certain characters

Question

I decided to do a test for how many different characters I could write. I tried this code:

for (int i = 0;i < 255;i++) {
    myBufferedWriter.write(i);
}

But in the file, using my hex editor, I saw it counted normally at first 01, 02, 03..., but then it got to 3F, and wrote that around 20 times, and then continued writing normally. Can I not write certain characters? I want to be able to write all characters 0-255.

Full code:

public class Main {
    public static void main(String[] args) {
        try{
            BufferedWriter bw = new BufferedWriter(new FileWriter(new File("abc.txt")));
            for (int i = 0;i < 255;i++) {
                bw.write(i);
            }
            bw.close();
          }catch(Exception e){}
    }
}

@jlordo It does that in any editor. I tried two others. If it was showing the wrong things, then it wouldn't be an hex editor. — Susan Yanders
– Susan Yanders, Commented Jul 4, 2013 at 23:33
oh-oh. I didn't look close enough. I have the same output as you. I'll do some research and post an answer. — jlordo
– jlordo, Commented Jul 4, 2013 at 23:35
No need to put the answer into the question ... especially since it is not necessarily the best answer. I edited it out. — Stephen C
– Stephen C, Commented Jul 5, 2013 at 1:35

Stephen C · Accepted Answer · 2013-08-14 23:46:13Z

4

I think your problem is that you are using the wrong API. What is happening with your current code is that your "characters" are being treated as text and encoded using the default character encoding for your platform.

If you want to write data in binary form (e.g. the bytes zero through 255) then you should be using the OutputStream APIs. Specifically BufferedOutputStream.

For example:

public class Main {
    public static void main(String[] args) throws IOException {
        BufferedOutputStream bos = new BufferedOutputStream(
                new FileOutputStream(new File("abc.dat")));
        for (int i = 0; i < 255; i++) {
            bos.write(i);
        }
        bos.close();
    }
}

If you want to be able to write other data types too (in binary form), then DataOutputStream is more appropriate ... because it has a bunch of other methods for writing primitive types and so on. However, if you want to write efficiently you need a BufferedOutputStream in between the FileOutputStream and the DataOutputStream.

edited Aug 14, 2013 at 23:46

answered Jul 4, 2013 at 23:28

Stephen C

723k95 gold badges849 silver badges1.3k bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Susan Yanders Over a year ago

How do I write to a file using an output stream?

user207421 Over a year ago

@SusanYanders OutputStream.write(). +1 for this answer.

Susan Yanders · Accepted Answer · 2013-07-04 23:51:27Z

0

I figured it out. My new code:

public class Main {
    public static void main(String[] args) {
        try{
            DataOutputStream dos = new DataOutputStream(new FileOutputStream(new File("abc.txt")));
            for (int i = 0;i < 255;i++)
                dos.writeByte(i);
            dos.close();
        }catch(Exception e){}
    }
}

answered Jul 4, 2013 at 23:51

Susan Yanders

8741 gold badge9 silver badges18 bronze badges

3 Comments

Stephen C Over a year ago

There are two problems with this code: 1) You aren't doing any buffering so each byte written will do a system call. 2) You are squashing all exceptions - BAD IDEA.

Susan Yanders Over a year ago

@StephenC I know about that. right now it isnt important. And in c++ you can hardly use exceptions anyways

Stephen C Over a year ago

It is only unimportant if you don't have any bugs that might throw exceptions. If there are bugs, then your code will silently erase any evidence. I don't think this should ever be dismissed as unimportant ... unless you are one of those rare people who actually enjoys tracking down obscure bugs.

Collectives™ on Stack Overflow

Java BufferedWriter can't write certain characters

2 Answers 2

2 Comments

3 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

3 Comments

Your Answer

Sign up or log in

Post as a guest

Related