Behavior of java.io.FileOutputStream.getChannel() does not match the spec

[Rémi Forax]

On 02/17/2011 10:34 AM, Alan Bateman wrote:
> Sean Chou wrote:
>> Hi,
>>    I find there is a mismatch between the spec and the behavior of
>> java.io.FileOutputStream.getChannel().
>>
>>    The spec reads: "The initial position of the returned channel will be
>> equal to the number of bytes written to the file so far unless this
>> stream is in append mode, in which case it will be equal to the size
>> of the file. "
>>
>>    But we'll get size 0 in such situation. Here is the testcase:
>>
>> //Testcase
>> import java.io.*;
>>
>> public class  FileOutputStreamTest{
>>    public static void main(String args[]) throws Exception{
>>         File tmpfile = File.createTempFile("FileOutputStream", "tmp");
>>         tmpfile.deleteOnExit();
>>         FileOutputStream fos = new FileOutputStream(tmpfile, false);
>>         fos.write(new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 });
>>         fos.close();
>>
>>         fos = new FileOutputStream(tmpfile, true);
>>         long size = fos.getChannel().position();
>>         if (10 != size){
>>                // This return value is 0, mismatching the spec
>>                System.out.println("Position Error Detected: except 
>> 10, but was " + size);
>>         }
>>         fos.close();
>>    }
>> }
>> // End of the testcase
>>
>>     Any comments?
>>
> This is a long standing issue, 6526860 but hasn't been high priority 
> as it probably isn't too common to query or change the file position 
> when opened for append.
>
> -Alan.

Anyway, it's a good idea to fix it :)

Rémi