create empty dataframe in scala and java

spark-empty-df.scala

import org.apache.spark.sql.types.{
    StructType, StructField, StringType, IntegerType}
import org.apache.spark.sql.Row

//in scala
val schema = StructType(
    StructField("k", StringType, true) ::
    StructField("v", IntegerType, false) :: Nil)

// Spark < 2.0
// sqlContext.createDataFrame(sc.emptyRDD[Row], schema) 
spark.createDataFrame(sc.emptyRDD[Row], schema)

//in java
sparkSession.createDataFrame(
    sparkSession.sparkContext().emptyRDD(scala.reflect.ClassTag$.MODULE$.apply(Row.class)),
    new StructType()
        .add(new StructField("uid", DataTypes.LongType, true, Metadata.empty()))
)