Hello,
As part of Project Lambda, a FunctionalInterface annotation type was
added to the platform to mark interfaces that are intended to be used in
lambda expressions. I've sent out a code review request to add this
annotation to types in the core-libs area [1] and have just pushed the
changeset into TL [2].
To assist the 2D team in adding analogous annotations to your types, the
list of candidate types in for 2D-related classes in java.* and javax.*
is given below. I recommend sub-tasks of JDK-8005297 "Add
FunctionalInterface support to the platform" be used to track the work
of adding @FunctionalInterface annotations to 2D types
In terms of how the annotation should be used, the benefit of the
annotation is that is clearly documents the type is intended to be used
for lambda expressions and is unlikely to evolve such that is cannot be
used with lambda expressions.
To a first approximation, if a candidate type today is commonly created
using anonymous inner classes, it is reasonable to add the
functionalInterface annotation. Note that the compiler will allow any
type meeting the structural requirements of a functional interface to be
used in a lambda expression; the annotation just provides documentation
of intent.
Having misplaced my 2D vs AWT vs Swing decoder ring, consideration of
these 2D types was previously sent to other aliases [3] [4].
Thanks,
-Joe
[1]
http://mail.openjdk.java.net/pipermail/core-libs-dev/2013-February/014292.html
[2] http://hg.openjdk.java.net/jdk8/tl/jdk/rev/522fb3867a3a
[3] http://mail.openjdk.java.net/pipermail/awt-dev/2013-February/004213.html
[4]
http://mail.openjdk.java.net/pipermail/swing-dev/2013-February/002535.html
-=-=-=-=-
jdk/src/share/classes/java/awt/Stroke.java:58: Note: Candidate
functional interface
public interface Stroke {
^
jdk/src/share/classes/java/awt/image/TileObserver.java:39: Note:
Candidate functional interface
public interface TileObserver {
jdk/src/share/classes/java/awt/image/ImageObserver.java:40: Note:
Candidate functional interface
public interface ImageObserver {
^
jdk/src/share/classes/java/awt/image/renderable/RenderedImageFactory.java:47:
Note: Candidate functional interface
public interface RenderedImageFactory {
^
jdk/src/share/classes/java/awt/image/TileObserver.java:39: Note:
Candidate functional interface
public interface TileObserver {
jdk/src/share/classes/java/awt/print/Printable.java:105: Note: Candidate
functional interface
public interface Printable {
^
jdk/src/share/classes/java/awt/PrintGraphics.java:33: Note: Candidate
functional interface
public interface PrintGraphics {
^
jdk/src/share/classes/javax/print/FlavorException.java:39: Note:
Candidate functional interface
public interface FlavorException {
^
jdk/src/share/classes/javax/print/event/PrintServiceAttributeListener.java:37:
Note: Candidate functional interface
public interface PrintServiceAttributeListener {
^
jdk/src/share/classes/javax/print/event/PrintJobAttributeListener.java:34:
Note: Candidate functional interface
public interface PrintJobAttributeListener {
^
jdk/src/share/classes/javax/imageio/IIOParamController.java:99: Note:
Candidate functional interface
public interface IIOParamController {
^
jdk/src/share/classes/javax/imageio/event/IIOWriteWarningListener.java:46:
Note: Candidate functional interface
public interface IIOWriteWarningListener extends EventListener {
^
jdk/src/share/classes/javax/imageio/event/IIOReadWarningListener.java:46: Note:
Candidate functional interface
public interface IIOReadWarningListener extends EventListener {
^
jdk/src/share/classes/javax/imageio/metadata/IIOMetadataController.java:67:
Note: Candidate functional interface
public interface IIOMetadataController {
^
jdk/src/share/classes/javax/imageio/spi/ServiceRegistry.java:464: Note:
Candidate functional interface
public interface Filter {
