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 an ALPHA 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.classification  
org.apache.spark.ml.evaluation  
org.apache.spark.ml.feature  
org.apache.spark.ml.param  
org.apache.spark.ml.tuning  
org.apache.spark.mllib.classification  
org.apache.spark.mllib.clustering  
org.apache.spark.mllib.evaluation  
org.apache.spark.mllib.evaluation.binary  
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.correlation  
org.apache.spark.mllib.stat.test  
org.apache.spark.mllib.tree  
org.apache.spark.mllib.tree.configuration  
org.apache.spark.mllib.tree.impl  
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.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.graphx.util.collection  
org.apache.spark.input  
org.apache.spark.io
IO codecs used for compression.
org.apache.spark.mapred  
org.apache.spark.mapreduce  
org.apache.spark.metrics  
org.apache.spark.metrics.sink  
org.apache.spark.metrics.source  
org.apache.spark.ml.impl.estimator  
org.apache.spark.ml.recommendation  
org.apache.spark.ml.regression  
org.apache.spark.mllib.classification.impl  
org.apache.spark.mllib.fpm  
org.apache.spark.mllib.impl  
org.apache.spark.mllib.regression.impl  
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.cluster.mesos  
org.apache.spark.scheduler.local  
org.apache.spark.serializer
Pluggable serializers for RDD and shuffle data.
org.apache.spark.sql  
org.apache.spark.sql.columnar  
org.apache.spark.sql.columnar.compression  
org.apache.spark.sql.hive  
org.apache.spark.sql.hive.execution  
org.apache.spark.sql.jdbc  
org.apache.spark.sql.json  
org.apache.spark.sql.parquet  
org.apache.spark.sql.parquet.timestamp  
org.apache.spark.sql.sources  
org.apache.spark.sql.test  
org.apache.spark.sql.types  
org.apache.spark.storage  
org.apache.spark.streaming  
org.apache.spark.streaming.dstream
Various implementations of DStreams.
org.apache.spark.streaming.rdd  
org.apache.spark.streaming.receiver  
org.apache.spark.streaming.scheduler  
org.apache.spark.streaming.ui  
org.apache.spark.streaming.util  
org.apache.spark.ui  
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.io  
org.apache.spark.util.logging  
org.apache.spark.util.random
Utilities for random number generation.