RFR: JDK-8161230 ClassLoader: add resource methods returning java.util.stream.Stream

Mandy Chung mandy.chung at oracle.com
Fri Sep 2 21:11:21 UTC 2016

> On Sep 2, 2016, at 2:50 AM, Patrick Reinhart <patrick at reini.net> wrote:
> Updated the existing http://cr.openjdk.java.net/~reinhapa/reviews/8161230/webrev.01

ClassLoader::resources returning Stream<URL> is a good addition. 
1386      * {@code IOException} occur getting the next resource element, it must be 
1387      * wrapped into an {@code UncheckedIOException}.

This has been mentioned in the paragraph above. This can be dropped from @apiNote. And add:

@throws UncheckedIOException if I/O errors occur

1392      * @return  An stream of resource {@link java.net.URL {@code URL}}

{@code…} is not needed as @link generates the text in <code>..</code> format.  You can simply write:
   {@link java.net.URL URL}

typo s/An/A

I’m unsure if “resource URL” clearly describes it.  What about
   @return A stream of {@code URL} representing the location of the resources with the given name.

1399      * @since  1.9

should be @since 9.

I have reservation in adding ClassLoader::systemResources static method.

ClassLoader::getSystemResources is a convenient method that is equivalent to calling ClassLoader::getSystemClassLoader().getResources(), since the system class loader is never null.  This method includes the resources in the application’s classpath.

With the new ClassLoader::getPlatformClassLoader() method, a better way to get the “system” resources from JDK (not the ones from the classpath), it can call:

To get a Stream of URL of the resources visible to system class loader, it can call the new resources method:

So it doesn’t seem that the proposed systemResources static method is necessary.

I suggest to combine the two tests in a single test, ResourcesStreamTest and add @bug JBS-id


  46         List<URL> resources = stream.collect(Collectors.toList());
  52         URL url = resources.get(0);

You can check the size first.  This can be simplified to use filter/findFirst to file the expected URL (yes need to call cl.resources again that is not an issue).

P.S. process wide - RDP1 starts.  This enhancement would need a sponsor and also request for approval [1].  I’m off for the long weekend and will follow up next Tuesday on this.

[1] http://openjdk.java.net/projects/jdk9/fc-extension-process

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