Closing the Stream returned from BufferedReader.lines()

Henry Jen henry.jen at
Mon Dec 2 10:45:51 PST 2013

On Mon 02 Dec 2013 04:02:33 AM PST, Millies, Sebastian wrote:
> In that context, I'd be in favor
> either of Gernot Neppert's suggestion in
> to add a default method,
> or of making the static utility method java.nio.file.Files#asUncheckedRunnable(Closeable)
> public somewhere.

We thought about this before, but decided to leave it out because,

1. If a close method is known to throw exceptions,  developer shoule 
deal with it.
2. It's trivial to add a static method to wrap up close if don't care 
consequences or add a utility class to cascade the exception.

That said, I think a default method to simply close resource regardless 
would be convenient if name clashing is not a concern.


> Otherwise many people will repeatedly have to write their own code in order to make
> the example  suggested by Brian Goetz in that core-libs-dev discussion compile.
> Is it too late for such changes?
> -- Sebastian
> -----Original Message-----
> From: lambda-dev-bounces at [mailto:lambda-dev-bounces at] On Behalf Of Alan Bateman
> Sent: Monday, December 02, 2013 10:21 AM
> To: Zhong Yu
> Cc: lambda-dev at
> Subject: Re: Closing the Stream returned from BufferedReader.lines()
> On 02/12/2013 03:03, Zhong Yu wrote:
>> In this code
>>           BufferedReader br = ...;
>>           Stream<String>  stream = br.lines();
>>           stream.close();  // does not close `br`
>> `stream.close()` does not trigger `br.close()`. I for one find that
>> rather counter-intuitive. Can you guys explain the design choice? When
>> should a Stream forward close() to its source and when should it not?
> See discussion on core-libs-dev from about a week ago on the same topic:
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