diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/typedaggregators.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/typedaggregators.scala
index 1dae5f6964e56..307321cb5b9df 100644
--- a/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/typedaggregators.scala
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/aggregate/typedaggregators.scala
@@ -17,72 +17,70 @@
 
 package org.apache.spark.sql.execution.aggregate
 
+import scala.reflect.runtime.universe.TypeTag
+
 import org.apache.spark.api.java.function.MapFunction
 import org.apache.spark.sql.{Encoder, TypedColumn}
 import org.apache.spark.sql.catalyst.encoders.ExpressionEncoder
 import org.apache.spark.sql.expressions.Aggregator
 
+
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 // This file defines internal implementations for aggregators.
 ////////////////////////////////////////////////////////////////////////////////////////////////////
 
+abstract class TypedAggregator[IN, BUF: TypeTag, OUT: TypeTag, JAVA]
+  extends Aggregator[IN, BUF, OUT] {
+
+  def bufferEncoder: Encoder[BUF] = ExpressionEncoder[BUF]()
+  def outputEncoder: Encoder[OUT] = ExpressionEncoder[OUT]()
+
+  def toColumnJava: TypedColumn[IN, JAVA] = {
+    toColumn.asInstanceOf[TypedColumn[IN, JAVA]]
+  }
+}
+
+class TypedSumDouble[IN](val f: IN => Double)
+  extends TypedAggregator[IN, Double, Double, java.lang.Double] {
 
-class TypedSumDouble[IN](val f: IN => Double) extends Aggregator[IN, Double, Double] {
   override def zero: Double = 0.0
   override def reduce(b: Double, a: IN): Double = b + f(a)
   override def merge(b1: Double, b2: Double): Double = b1 + b2
   override def finish(reduction: Double): Double = reduction
 
-  override def bufferEncoder: Encoder[Double] = ExpressionEncoder[Double]()
-  override def outputEncoder: Encoder[Double] = ExpressionEncoder[Double]()
-
-  // Java api support
+  // Java constructor
   def this(f: MapFunction[IN, java.lang.Double]) = this(x => f.call(x).asInstanceOf[Double])
-
-  def toColumnJava: TypedColumn[IN, java.lang.Double] = {
-    toColumn.asInstanceOf[TypedColumn[IN, java.lang.Double]]
-  }
 }
 
 
-class TypedSumLong[IN](val f: IN => Long) extends Aggregator[IN, Long, Long] {
+class TypedSumLong[IN](val f: IN => Long)
+  extends TypedAggregator[IN, Long, Long, java.lang.Long] {
+
   override def zero: Long = 0L
   override def reduce(b: Long, a: IN): Long = b + f(a)
   override def merge(b1: Long, b2: Long): Long = b1 + b2
   override def finish(reduction: Long): Long = reduction
 
-  override def bufferEncoder: Encoder[Long] = ExpressionEncoder[Long]()
-  override def outputEncoder: Encoder[Long] = ExpressionEncoder[Long]()
-
-  // Java api support
+  // Java constructor
   def this(f: MapFunction[IN, java.lang.Long]) = this(x => f.call(x).asInstanceOf[Long])
-
-  def toColumnJava: TypedColumn[IN, java.lang.Long] = {
-    toColumn.asInstanceOf[TypedColumn[IN, java.lang.Long]]
-  }
 }
 
+class TypedCount[IN](val f: IN => Any)
+  extends TypedAggregator[IN, Long, Long, java.lang.Long] {
 
-class TypedCount[IN](val f: IN => Any) extends Aggregator[IN, Long, Long] {
   override def zero: Long = 0
-  override def reduce(b: Long, a: IN): Long = {
-    if (f(a) == null) b else b + 1
-  }
+  override def reduce(b: Long, a: IN): Long = if (f(a) == null) b else b + 1
   override def merge(b1: Long, b2: Long): Long = b1 + b2
   override def finish(reduction: Long): Long = reduction
 
-  override def bufferEncoder: Encoder[Long] = ExpressionEncoder[Long]()
-  override def outputEncoder: Encoder[Long] = ExpressionEncoder[Long]()
-
-  // Java api support
+  // Java constructor
   def this(f: MapFunction[IN, Object]) = this(x => f.call(x))
-  def toColumnJava: TypedColumn[IN, java.lang.Long] = {
-    toColumn.asInstanceOf[TypedColumn[IN, java.lang.Long]]
-  }
+
 }
 
+class TypedAverage[IN](val f: IN => Double)
+  extends TypedAggregator[IN, (Double, Long), Double, java.lang.Double] {
 
-class TypedAverage[IN](val f: IN => Double) extends Aggregator[IN, (Double, Long), Double] {
   override def zero: (Double, Long) = (0.0, 0L)
   override def reduce(b: (Double, Long), a: IN): (Double, Long) = (f(a) + b._1, 1 + b._2)
   override def finish(reduction: (Double, Long)): Double = reduction._1 / reduction._2
@@ -90,12 +88,6 @@ class TypedAverage[IN](val f: IN => Double) extends Aggregator[IN, (Double, Long
     (b1._1 + b2._1, b1._2 + b2._2)
   }
 
-  override def bufferEncoder: Encoder[(Double, Long)] = ExpressionEncoder[(Double, Long)]()
-  override def outputEncoder: Encoder[Double] = ExpressionEncoder[Double]()
-
   // Java api support
   def this(f: MapFunction[IN, java.lang.Double]) = this(x => f.call(x).asInstanceOf[Double])
-  def toColumnJava: TypedColumn[IN, java.lang.Double] = {
-    toColumn.asInstanceOf[TypedColumn[IN, java.lang.Double]]
-  }
 }