8230342: LineNumberReader.getLineNumber() returns inconsistent results after EOF

[Roger Riggs]

Hi Brian,

Reconsidering...

If the current line number starts at zero and is incremented only by CR/LF
then my example program is wrong.  It called getLineNumber *after* reading
the line and it should have called it *before*.

So I can support your original patch (modulo not using AtomicBoolean).

(Though my suggestion about doing all the work of keeping track of the 
line number in BufferedReader
is still a valid though separate suggestion).

Roger


On 9/9/19 5:02 PM, Brian Burkhalter wrote:
> If we wanted to go the route of changing the spec to match the behavior, the additional verbiage below is one possibility.
>
> Thanks,
>
> Brian
>
> +++ b/src/java.base/share/classes/java/io/LineNumberReader.java
> @@ -35,19 +35,20 @@
>    * <p> By default, line numbering begins at 0. This number increments at every
>    * <a href="#lt">line terminator</a> as the data is read, and can be changed
>    * with a call to {@code setLineNumber(int)}.  Note however, that
>    * {@code setLineNumber(int)} does not actually change the current position in
>    * the stream; it only changes the value that will be returned by
>    * {@code getLineNumber()}.
>    *
>    * <p> A line is considered to be <a id="lt">terminated</a> by any one of a
>    * line feed ('\n'), a carriage return ('\r'), or a carriage return followed
> - * immediately by a linefeed.
> + * immediately by a linefeed. For {@link #readLine()} only, the end of the
> + * stream is also considered to be a line terminator.
>
>   
>   public class LineNumberReader extends BufferedReader {
>   
>       /** The current line number */
>       private int lineNumber = 0;
> @@ -183,19 +184,21 @@
>                   }
>               }
>   
>               return n;
>           }
>       }
>   
>       /**
>        * Read a line of text.  Whenever a <a href="#lt">line terminator</a> is
> -     * read the current line number is incremented.
> +     * read the current line number is incremented.  Unlike for the other
> +     * {@code read} methods of this class, reaching the end of the stream
> +     * will also increment the current line number.
>        *
>        * @return  A String containing the contents of the line, not including
>        *          any <a href="#lt">line termination characters</a>, or
>        *          {@code null} if the end of the stream has been reached
>        *
>        * @throws  IOException
>        *          If an I/O error occurs
>        */
>       public String readLine() throws IOException {
>
>> On Sep 9, 2019, at 12:02 PM, Brian Burkhalter <brian.burkhalter at oracle.com> wrote:
>>
>>> On Sep 9, 2019, at 7:35 AM, Roger Riggs <Roger.Riggs at oracle.com <mailto:Roger.Riggs at oracle.com>> wrote:
>>>
>>> I would lean toward updating the spec to reflect the current implementation.
>> It seems strange however that if one read an entire stream using read() in one case and readLine() in another that the results would differ.