[FLINK-3444] env.fromElements relies on the first input element for determining the DataSet/DataStream type

• Type: Bug
• Status: Closed
• Priority: Major
• Resolution: Fixed
• Affects Version/s: 0.10.0, 1.0.0
• Fix Version/s: 1.1.0
• Component/s: API / DataSet, API / DataStream
• Assignee: Unassigned
• Reporter: Vasia Kalavri
• Created: 18/Feb/16 19:49
• Updated: 29/Apr/16 11:55
• Resolved: 13/Apr/16 08:46

Description

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

DataStream<Event> input = env.fromElements(new Event(1, "a"), new SubEvent(2, "b"));

succeeds, while the following

DataStream<Event> input = env.fromElements(new SubEvent(1, "a"), new Event(2, "b"));

fails with "java.lang.IllegalArgumentException: The elements in the collection are not all subclasses of SubEvent".