diff --git a/jvm-packages/checkstyle-suppressions.xml b/jvm-packages/checkstyle-suppressions.xml
index 28aed4fab..4a0f9ab33 100644
--- a/jvm-packages/checkstyle-suppressions.xml
+++ b/jvm-packages/checkstyle-suppressions.xml
@@ -29,5 +29,5 @@
 
 <suppressions>
 <suppress checks=".*"
-	files="xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XGBoostJNI.java"/>
+files="xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XGBoostJNI.java"/>
 </suppressions>
diff --git a/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/DataUtils.scala b/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/DataUtils.scala
index fd336a9c2..4ad951567 100644
--- a/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/DataUtils.scala
+++ b/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/DataUtils.scala
@@ -21,7 +21,7 @@ import java.util.{Iterator => JIterator}
 import scala.collection.mutable.ListBuffer
 import scala.collection.JavaConverters._
 
-import ml.dmlc.xgboost4j.DataBatch
+import ml.dmlc.xgboost4j.java.DataBatch
 import org.apache.spark.mllib.linalg.{SparseVector, DenseVector, Vector}
 import org.apache.spark.mllib.regression.LabeledPoint
 
diff --git a/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoost.scala b/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoost.scala
index 96a6210a7..8151e6ccc 100644
--- a/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoost.scala
+++ b/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoost.scala
@@ -20,7 +20,7 @@ import scala.collection.immutable.HashMap
 import scala.collection.JavaConverters._
 
 import com.typesafe.config.Config
-import ml.dmlc.xgboost4j.{DMatrix => JDMatrix}
+import ml.dmlc.xgboost4j.java.{DMatrix => JDMatrix}
 import ml.dmlc.xgboost4j.scala.{XGBoost => SXGBoost, _}
 import org.apache.spark.SparkContext
 import org.apache.spark.mllib.regression.LabeledPoint
@@ -48,7 +48,9 @@ object XGBoost {
         val dataBatches = dataUtilsBroadcast.value.fromLabeledPointsToSparseMatrix(trainingSamples)
         val dMatrix = new DMatrix(new JDMatrix(dataBatches, null))
         Iterator(SXGBoost.train(xgBoostConfigMap, dMatrix, round, watches = null, obj, eval))
-    }
+    }.cache()
+    // force the job
+    sc.runJob(boosters, (boosters: Iterator[Booster]) => boosters)
     // TODO: how to choose best model
     boosters.first()
   }
diff --git a/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoostModel.scala b/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoostModel.scala
index 849ad6168..47efb053f 100644
--- a/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoostModel.scala
+++ b/jvm-packages/xgboost4j-spark/src/main/scala/ml/dmlc/xgboost4j/scala/spark/XGBoostModel.scala
@@ -18,7 +18,7 @@ package ml.dmlc.xgboost4j.scala.spark
 
 import scala.collection.JavaConverters._
 
-import ml.dmlc.xgboost4j.{DMatrix => JDMatrix}
+import ml.dmlc.xgboost4j.java.{DMatrix => JDMatrix}
 import ml.dmlc.xgboost4j.scala.{DMatrix, Booster}
 import org.apache.spark.mllib.regression.LabeledPoint
 import org.apache.spark.rdd.RDD
diff --git a/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XgboostJNI.java b/jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XGBoostJNI.java
similarity index 100%
rename from jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XgboostJNI.java
rename to jvm-packages/xgboost4j/src/main/java/ml/dmlc/xgboost4j/java/XGBoostJNI.java