FileNotFoundException on opening FileOutputStream on same file read using java nio

I have a text editor that uses code almost identical to the below for reading and writing. When I open small files for editting, I always get this error when I try to save them again. The really interesting thing though is that my text editor works fine for files with about 600 bytes or more (seems to vary eac开发者_C百科h time), behaviour that I haven't been able to replicate here.

My current workaround is to check for file size < 1024 bytes, and use java.io if that's the case.

import java.io.*;
import java.nio.*;
import java.nio.channels.*;
import java.nio.charset.*;

public class Test {
    public static void main(String[] args) {
        String text = null;
        try {
            FileInputStream fis = new FileInputStream("test.txt");
            FileChannel ifc = fis.getChannel();
            CharBuffer cb = Charset.forName("ISO-8859-15").newDecoder().
                    decode(ifc.map(FileChannel.MapMode.READ_ONLY, 0,
                    (int) ifc.size()));
            text = cb.toString();
            ifc.close();
            fis.close();
        } catch (IOException ex) {
            ex.printStackTrace();
        }

        try {
            FileOutputStream fos = new FileOutputStream("test.txt");
            OutputStreamWriter osw = new OutputStreamWriter(
                    fos, "ISO-8859-15");
            osw.write(text);
            osw.close();
            fos.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

For the above code, I get this error for various sizes of test.txt from 4 bytes to 10kb:

java.io.FileNotFoundException: test.txt (The requested operation cannot be perfo
rmed on a file with a user-mapped section open)
        at java.io.FileOutputStream.open(Native Method)
        at java.io.FileOutputStream.<init>(Unknown Source)
        at java.io.FileOutputStream.<init>(Unknown Source)
        at Test.main(Test.java:23)

Can anyone explain what I'm doing wrong and how I can get this to work while still reading with nio?

---

Stephen C told you to unmap the buffer.

However, here is a link to STILL OPEN ( from 2002 ) request for MappedBybeBuffer.unmap method.

It has a few workarounds suggested, so you may try them.

---

You need to explicitly unmap the region that you mapped with the FileChannel.map(...) call.

The Javadoc for map(...) says this:

A mapping, once established, is not dependent upon the file channel that was used to create it. Closing the channel, in particular, has no effect upon the validity of the mapping.