ARM API Support
Joe Darcy
joe.darcy at oracle.com
Tue Jul 13 19:47:26 PDT 2010
PS Additional platform classes have been retrofitted for use with ARM
(http://hg.openjdk.java.net/jdk7/tl/jdk/rev/425960cef714):
Retrofit as AutoCloseable:
java.beans.XMLEncoder
java.beans.XMLDecoder
java.io.ObjectInput
java.io.ObjectOutput
javax.sound.sampled.Line
javax.sound.midi.Receiver
javax.sound.midi.Transmitter
javax.sound.midi.MidiDevice
Retrofit as Closeable:
java.util.Scanner
Candidates for retrofitting were identified by running an annotation
processor over the JDK sources; for details see:
"Project Coin: Bringing it to a Close(able)"
http://blogs.sun.com/darcy/entry/project_coin_bring_close
-Joe
Joe Darcy wrote:
> Greetings
>
> The initial API changes to support the Project Coin feature automatic
> resource management (ARM) blocks have been pushed into JDK 7 [1] and
> will appear in subsequent builds. The corresponding compiler changes
> to support the actual language feature remain in progress.
>
> The initial API work to support ARM was divided into two pieces,
> essential API support and retrofitting platform classes. The essential
> support includes:
>
> * A new interface java.lang.AutoCloseable which defines a single method
> void close() throws Exception
>
> * A new enum constant in the language model:
> javax.lang.model.element.ElementKind.RESOURCE_VARIABLE
>
> * Methods on java.lang.Throwable to add and retrieve information about
> suppressed exceptions, including printing out suppressed exceptions in
> stack traces.
>
> The retrofitting includes:
>
> * Having java.io.Closeable extend java.lang.AutoCloseable. (From a
> typing perspective, a subtype of AutoCloseable can be declared to
> throw fewer exceptions than the supertype. Therefore is is fine for
> the close method in AutoCloseable to throw Exception and the close
> method in Closeable to throw the more specific IOException. It would
> even be fine for the close method in a subtype of AutoCloseable to be
> declared to throw no exceptions at all.)
>
> * Adding a close method to java.nio.channels.FileLock and having
> FileLock implement AutoCloseable.
>
> * Adding Closeable as an interface implemented by
> javax.imageio.stream.ImageInputStream.
>
> Other platform classes may be retrofitted to implement AutoCloseable
> or Closable in future builds.
>
> Compared to the API support in earlier versions of the ARM proposal,
> the top-level interface to mark participation in ARM is in package
> java.lang rather than its own package and, after consultation with the
> JDBC and graphics teams, neither java.sql.* nor java.awt.Graphics were
> retrofitted for ARM.
>
> -Joe
>
> [1] http://hg.openjdk.java.net/jdk7/tl/jdk/rev/c4d60bcce958
> http://hg.openjdk.java.net/jdk7/tl/langtools/rev/be5cafeb318d
>
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