[FLINK-1458] Interfaces and abstract classes are not valid types

• Type: Bug
• Status: Resolved
• Priority: Major
• Resolution: Duplicate
• Assignee: Aljoscha Krettek
• Reporter: John Sandiford
• Created: 27/Jan/15 18:37
• Updated: 18/Aug/16 12:21
• Resolved: 27/Jan/15 21:01

Description

I don't know whether this is by design or is a bug, but I am having trouble working with DataSet and traits in scala which is a major limitation. A simple example is shown below.

Compile time warning is 'Type Main.SimpleTrait has no fields that are visible from Scala Type analysis. Falling back to Java Type Analysis...'

Run time error is 'Interfaces and abstract classes are not valid types: interface Main$SimpleTrait'

Regards, John

val env = ExecutionEnvironment.getExecutionEnvironment

trait SimpleTrait

{ def contains(x: String): Boolean }

class SimpleClass extends SimpleTrait

{ def contains(x: String) = true }

val data: DataSet[Double] = env.fromElements(1.0, 2.0, 3.0, 4.0)

def f(data: DataSet[Double]): DataSet[SimpleTrait] = {

data.mapPartition(iterator =>

{ Iterator(new SimpleClass) }

)
}

val g = f(data)
g.print()

env.execute("Simple example")

Issue Links

• links to: GitHub Pull Request #357