Problem with Writer.flush() appending extra character

Question

I have written a simple file copy that does the following:
     public static void copy(File source, File dest) throws IOException
          FileReader fr = new FileReader(source);
          FileWriter fw = new FileWriter(dest);
          try
               char[] ch = new char[(int)source.length()];
               fr.read(ch);
               fw.write(ch);
          finally
               fr.close();
               fw.close();
It works fine, and has done for some time.
For some reason, in a recent data collection, I have 3 files out of about a hundred, where the following behaviour occurs.
The char array is written to the file fine. For some reason when fw.flush() is called (i have tested this and confirmed that it is the call to flush() that is causing it) it appends a char to the end of the file with a value of -1.
This is causing merry havoc with my XML parser.
Can anybody tell me how to stop Writer from adding a -1 to my file?
This is on java 1.4.2 currently.

Answer 1

               char[] ch = new char[(int)source.length()];File.length() returns the number of bytes in the file.
However, you're loading that file via a Reader, which converts those bytes into characters using some encoding method. Depending on the encoding, the number of characters produced may be completely different from the number of bytes read. It's also possible that the bytes read are not valid with the encoding.
If you're just copying files, use FileInputStream and FileOutputStream. Better, download the Jakarta Commons IO library, and use their already-tested methods.
If you're working with a JAXP XML parser (ie, what comes with JDK 1.4 and above), create your InputSource from a FileInputStream. That will let the XML parser use the encoding specified in the file, ignoring whatever your JRE's default encoding is.
If you're planning to work with the raw text, then you're going to have to learn about character encodings. I don't have a tutorial link handy, so either Google for one or start with the documentation for java.nio.charset.Charset.