Core Java API 
Package Description
org.apache.spark.api.java
Spark Java programming APIs.
org.apache.spark.api.java.function
Set of interfaces to represent functions in Spark's Java API.
Spark Streaming 
Package Description
org.apache.spark.streaming.api.java
Java APIs for spark streaming.
org.apache.spark.streaming.flume
Spark streaming receiver for Flume.
org.apache.spark.streaming.kafka
Kafka receiver for spark streaming.
org.apache.spark.streaming.kinesis  
org.apache.spark.streaming.mqtt
MQTT receiver for Spark Streaming.
org.apache.spark.streaming.twitter
Twitter feed receiver for spark streaming.
org.apache.spark.streaming.zeromq
Zeromq receiver for spark streaming.
MLlib 
Package Description
org.apache.spark.ml
Spark ML is a BETA component that adds a new set of machine learning APIs to let users quickly assemble and configure practical machine learning pipelines.
org.apache.spark.ml.attribute
ML attributes
org.apache.spark.ml.classification  
org.apache.spark.ml.evaluation  
org.apache.spark.ml.feature  
org.apache.spark.ml.param  
org.apache.spark.ml.recommendation  
org.apache.spark.ml.regression  
org.apache.spark.ml.tuning  
org.apache.spark.mllib.classification  
org.apache.spark.mllib.clustering  
org.apache.spark.mllib.evaluation  
org.apache.spark.mllib.feature  
org.apache.spark.mllib.linalg  
org.apache.spark.mllib.linalg.distributed  
org.apache.spark.mllib.optimization  
org.apache.spark.mllib.random  
org.apache.spark.mllib.rdd  
org.apache.spark.mllib.recommendation  
org.apache.spark.mllib.regression  
org.apache.spark.mllib.stat  
org.apache.spark.mllib.stat.test  
org.apache.spark.mllib.tree  
org.apache.spark.mllib.tree.configuration  
org.apache.spark.mllib.tree.impurity  
org.apache.spark.mllib.tree.loss  
org.apache.spark.mllib.tree.model  
org.apache.spark.mllib.util  
Spark SQL 
Package Description
org.apache.spark.sql.api.java
Allows the execution of relational queries, including those expressed in SQL using Spark.
Other Packages 
Package Description
org.apache.spark
Core Spark classes in Scala.
org.apache.spark.annotation
Spark annotations to mark an API experimental or intended only for advanced usages by developers.
org.apache.spark.api.r  
org.apache.spark.broadcast
Spark's broadcast variables, used to broadcast immutable datasets to all nodes.
org.apache.spark.examples.streaming  
org.apache.spark.graphx
ALPHA COMPONENT GraphX is a graph processing framework built on top of Spark.
org.apache.spark.graphx.impl  
org.apache.spark.graphx.lib
Various analytics functions for graphs.
org.apache.spark.graphx.util
Collections of utilities used by graphx.
org.apache.spark.input  
org.apache.spark.io
IO codecs used for compression.
org.apache.spark.launcher
Library for launching Spark applications.
org.apache.spark.ml.tree  
org.apache.spark.mllib.fpm  
org.apache.spark.mllib.pmml  
org.apache.spark.mllib.stat.distribution  
org.apache.spark.partial  
org.apache.spark.rdd
Provides implementation's of various RDDs.
org.apache.spark.scheduler
Spark's DAG scheduler.
org.apache.spark.scheduler.cluster  
org.apache.spark.scheduler.local  
org.apache.spark.serializer
Pluggable serializers for RDD and shuffle data.
org.apache.spark.sql  
org.apache.spark.sql.expressions  
org.apache.spark.sql.hive  
org.apache.spark.sql.jdbc  
org.apache.spark.sql.json  
org.apache.spark.sql.sources  
org.apache.spark.sql.test  
org.apache.spark.sql.types  
org.apache.spark.status.api.v1  
org.apache.spark.storage  
org.apache.spark.streaming  
org.apache.spark.streaming.dstream
Various implementations of DStreams.
org.apache.spark.streaming.receiver  
org.apache.spark.streaming.scheduler  
org.apache.spark.streaming.ui  
org.apache.spark.streaming.util  
org.apache.spark.ui.env  
org.apache.spark.ui.exec  
org.apache.spark.ui.jobs  
org.apache.spark.ui.storage  
org.apache.spark.util
Spark utilities.
org.apache.spark.util.random
Utilities for random number generation.