CODEWITHSUNDEEP
scala
autodidacticon
autodidacticon

Reputation: 1358

No ClassTag available for T

import org.apache.spark.api.java.JavaRDD
import org.apache.spark.rdd.RDD
import scala.reflect.ClassTag  

class TestRDD[T: ClassTag](rdd: RDD[T]) extends JavaRDD(rdd)

This statement is accepted from the console. However at compile time the following error is thrown:

No ClassTag available for T
[error] class TestRDD[T: ClassTag](rdd: RDD[T]) extends JavaRDD(rdd)
[error]                ^
[error] one error found
[error] (jobs/it:compileIncremental) Compilation failed

Upvotes: 8

Views: 6466

Answers (3)

autodidacticon
autodidacticon

Reputation: 1358

Well this is the embarassing solution:

class TestRDD[T: ClassTag](rdd: RDD[T]) extends RDD[T](rdd: RDD[T])

Upvotes: 2

chengpohi
chengpohi

Reputation: 14217

I think you want this:

class TestRDD[T](rdd: List[T])(implicit c: ClassTag[T]) extends JavaRDD(rdd)

use implicit to auto implicit the ClassTag of generic T.

Upvotes: 12

Zang MingJie
Zang MingJie

Reputation: 5275

Due to jvm template type erase, the compiler can't get type information of T from rdd.

But type information of T is stored in class RDD, maybe you can get the classtag of T from RDD class

Upvotes: 0

Related Questions