SI-9113 Converting null collection Java<->Scala yields null
#4343
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`scala.collection.{JavaConversions, JavaConverters}` no longer wrap
a `null` collection, but return `null` instead. Before, a wrapper would
hold the original `null` collections, delaying the NPE until the first
operation on the collection was called, with no way of knowing whether we
were holding such a time bomb wrapper until the NPE was thrown.
For example, this now holds: `(null : java.util.Iterator[_]).asScala ==
null`. Before, a wrapper would silently be created that would NPE on any
further interaction.
An example of this issue in the wild can be seen at
scalafx/scalafx#178, and an example of code
that generates such a wrapper [before the issue was fixed](https://github.com/scalafx/scalafx/blob/ad60d5faee687b71d3c0474510d
3f3dd081ea351/scalafx/src/main/scala/scalafx/stage/FileChooser.scala#L138).
|
LGTM. Slightly more tests than strictly needed, but they should be fast so this isn't a problem. |
|
Thank you, @RomanHargrave, for addressing this! Let's merge this and follow up for the other wrappers (tracked by https://issues.scala-lang.org/browse/SI-9176) |
adriaanm
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Feb 23, 2015
SI-9113 Converting `null` collection Java<->Scala yields `null`
This was referenced Apr 7, 2017
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Originally submitted for 2.11.x in #4267
scala.collection.{JavaConversions, JavaConverters}no longer wrapa
nullcollection, but returnnullinstead. Before, a wrapper wouldhold the original
nullcollections, delaying the NPE until the firstoperation on the collection was called, with no way of knowing whether we
were holding such a time bomb wrapper until the NPE was thrown.
For example, this now holds:
(null : java.util.Iterator[_]).asScala == null.Before, a wrapper would silently be created that would NPE on any further interaction.
An example of this issue in the wild can be seen at
scalafx/scalafx#178, and an example of code
that generates such a wrapper [before the issue was fixed](https://github.com/scalafx/scalafx/blob/ad60d5faee687b71d3c0474510d
3f3dd081ea351/scalafx/src/main/scala/scalafx/stage/FileChooser.scala#L138).