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https://issues.apache.org/jira/browse/FLINK-3444?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15227983#comment-15227983
]
ASF GitHub Bot commented on FLINK-3444:
---------------------------------------
Github user zentol commented on a diff in the pull request:
https://github.com/apache/flink/pull/1857#discussion_r58673287
--- Diff:
flink-java/src/main/java/org/apache/flink/api/java/ExecutionEnvironment.java ---
@@ -780,6 +780,33 @@ public CsvReader readCsvFile(String filePath) {
return fromCollection(Arrays.asList(data),
TypeExtractor.getForObject(data[0]), Utils.getCallLocationName());
}
+ /**
+ * Creates a new data set that contains the given elements. The
elements must all be of the same type,
+ * for example, all of the {@link String} or {@link Integer}. The
sequence of elements must not be empty.
+ * <p>
+ * The framework will try and determine the exact type from the
collection elements.
+ * In case of generic elements, it may be necessary to manually supply
the type information
+ * via {@link #fromCollection(Collection, TypeInformation)}.
+ * <p>
+ * Note that this operation will result in a non-parallel data source,
i.e. a data source with
+ * a parallelism of one.
+ *
+ * @param type The base class type for every element in the collection.
+ * @param data The elements to make up the data set.
+ * @return A DataSet representing the given list of elements.
+ */
+ @SafeVarargs
+ public final <X> DataSource<X> fromElements(Class<X> type, X... data) {
+ if (data == null) {
+ throw new IllegalArgumentException("The data must not
be null.");
+ }
+ if (data.length == 0) {
+ throw new IllegalArgumentException("The number of
elements must not be zero.");
+ }
+
+ return fromCollection(Arrays.asList(data),
TypeExtractor.getForClass(type), Utils.getCallLocationName());
--- End diff --
why does the scala variant throw a specific exception on getForClass()
failure but this one doesn't?
> env.fromElements relies on the first input element for determining the
> DataSet/DataStream type
> ----------------------------------------------------------------------------------------------
>
> Key: FLINK-3444
> URL: https://issues.apache.org/jira/browse/FLINK-3444
> Project: Flink
> Issue Type: Bug
> Components: DataSet API, DataStream API
> Affects Versions: 0.10.0, 1.0.0
> Reporter: Vasia Kalavri
>
> The {{fromElements}} method of the {{ExecutionEnvironment}} and
> {{StreamExecutionEnvironment}} determines the DataSet/DataStream type by
> extracting the type of the first input element.
> This is problematic if the first element is a subtype of another element in
> the collection.
> For example, the following
> {code}
> DataStream<Event> input = env.fromElements(new Event(1, "a"), new SubEvent(2,
> "b"));
> {code}
> succeeds, while the following
> {code}
> DataStream<Event> input = env.fromElements(new SubEvent(1, "a"), new Event(2,
> "b"));
> {code}
> fails with "java.lang.IllegalArgumentException: The elements in the
> collection are not all subclasses of SubEvent".
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