JDK-8191706: Proposal to add Reader::transferTo(Writer)

[Brian Burkhalter]

Hi Patrick,

This looks fine from my point of view. It exactly mirrors InputStream.transferTo(OutputStream) with which I expect everyone will concur.

Thanks,

Brian

On Nov 21, 2017, at 11:56 AM, Patrick Reinhart <patrick at reini.net> wrote:

> Hi there out a the review [1] for  JDK-8066870, that will need some more
> working on, I created this specific issue to add an transferTo method to
> the java.io.Reader as it seems more clear as of the similarity to
> java.io.InputStream.transferTo(java.io.OutputStream) in terms of the API.
> 
> To start the discussion I got the proposed API:
> 
> /**
>  * Reads all characters from this reader and writes the characters to the
>  * given writer in the order that they are read. On return, this reader
>  * will be at end of the data. This method does not close either reader
>  * or writer.
>  * <p>
>  * This method may block indefinitely reading from the reader, or
>  * writing to the writer. The behavior for the case where the reader
>  * and/or writer is <i>asynchronously closed</i>, or the thread
>  * interrupted during the transfer, is highly reader and writer
>  * specific, and therefore not specified.
>  * <p>
>  * If an I/O error occurs reading from the reader or writing to the
>  * writer, then it may do so after some characters have been read or
>  * written. Consequently the reader may not be at end of the data and
>  * one, or both, streams may be in an inconsistent state. It is strongly
>  * recommended that both streams be promptly closed if an I/O error occurs.
>  *
>  * @param  out the writer, non-null
>  * @return the number of characters transferred
>  * @throws IOException if an I/O error occurs when reading or writing
>  * @throws NullPointerException if {@code out} is {@code null}
>  *
>  * @since 10
>  */
> public long transferTo(Writer out) throws IOException {
> ....
> }
> 
> 
> -Patrick
> 
> 
> [1]
> http://mail.openjdk.java.net/pipermail/core-libs-dev/2017-November/050064.html
> 
> 
> 
>