GitHub user michalsenkyr opened a pull request:
https://github.com/apache/spark/pull/18009
[SPARK-18891][SQL] Support for specific Java List subtypes
## What changes were proposed in this pull request?
Add support for specific Java `List` subtypes in deserialization as well as
a generic implicit encoder.
All `List` subtypes are supported by using either the size-specifying
constructor (one `int` parameter) or the default constructor.
Interfaces/abstract classes use the following implementations:
* `java.util.List`, `java.util.AbstractList` or
`java.util.AbstractSequentialList` => `java.util.ArrayList`
## How was this patch tested?
```bash
build/mvn -DskipTests clean package && dev/run-tests
```
Additionally in Spark shell:
```
scala> val jlist = new java.util.LinkedList[Int]; jlist.add(1)
jlist: java.util.LinkedList[Int] = [1]
res0: Boolean = true
scala> Seq(jlist).toDS().map(_.element()).collect()
res1: Array[Int] = Array(1)
```
You can merge this pull request into a Git repository by running:
$ git pull https://github.com/michalsenkyr/spark dataset-java-lists
Alternatively you can review and apply these changes as the patch at:
https://github.com/apache/spark/pull/18009.patch
To close this pull request, make a commit to your master/trunk branch
with (at least) the following in the commit message:
This closes #18009
----
commit 1cd6b6b4cdb0ff8a5cc42a105c7a8d4bc16fc0c1
Author: Michal Senkyr <[email protected]>
Date: 2017-04-16T15:54:40Z
Add arbitrary Java List serialization/deserialization support
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