Spark Java Examples

This project is created to learn Apache Spark Programming using Java. This project consists of the following examples:

• How to create SparkContext and SparkSession.
• Taking data from arrays and external file source.
• Spark Map Transformation.
• Spark Filter Transformation.
• Spark FlatMap Transformation.
• Compare Map and FlatMap.
• Set Operations.
• Spark Reduce Transformation.
• Spark Aggregate Transformation.
• Using Functions in Spark Transformation.
• Key Value RDD.
• Using HDFS

Data Sets

• cars.csv - A data set with many attributes of various car models.
• Some random array data.

Getting Started

These instructions will get you a brief idea on setting up the environment and running on your local machine for development and testing purposes.

Prerequisities

• Java
• Apache Spark
• Hadoop

Setup and running tests

1. Run javac and java -version to check the installation

2. Run spark-shell and check if Spark is installed properly.

3. Go to Hadoop user (If installed on different user) and run the following (On Ubuntu Systems):

   sudo su hadoopuser

   start-all.sh

4. Execute the following commands from terminal to run the tests:

   javac -classpath "Path to required jar files(spark, hadoop, scala)" Main.java

Classes

Please start exploring from Main.java

All classes in this project are listed below:

• CreateSpark.java - To create SparkContext and SparkSession. Contains the following methods:

        `public JavaSparkContext context(String appName, String master)`
        `public SparkSession session(String appName, String master)`

• ArrayData.java - Using array data to create JavaRDD and performs spark actions on it. Contains the following method:

        `public void callArrayData()`

• ExternalFileData.java - Using external file source to create JavaRDD and performs spark actions on it. Contains the following method:

  `public void callFileData(String filePath)`

• SparkMap.java - Example code on using Spark Map Transformation, contains the following method:

        `public void mapReplace(String arg0, String arg1)`

• SparkFilter.java - Example code on using Spark Filter Transformation, contains the following method:

  `public void callFilter(String str)`

• SparkFlatMap.java - Example code on using Spark FlatMap Transformation, contains the following method:

  `public void callFlatMap()`

• CompareMapAndFlatMap.java - To compare and understand Map and FlapMap Transformations. Contains the following method:

  `public void compare()`

• SetOperations.java - Performing set operations on JavaRDD. Contains the following method:

  `public void callSetOp()`

• Reduce.java - Examples on Spark Reduce Transformation. Contains the following methods:

  `public void sum()`    
  `public void shortestLine()`

• Aggregation.java - Uses two different use cases of Spark Aggregate Transformation. Contains the following methods:

  `public void sum()`    
  `public void sumAndProduct()` 

• Functions.java - Using Functions in Spark Transformation. Contains the following methods:

  `public static void example1(JavaSparkContext sparkContext)`
  `public static void example2(JavaSparkContext sparkContext)`

• KeyValueRDD.java - Examples on using Key Value RDD. Contains the following method:

  `public void callKVRDD()`

• UsingHDFS.java - Example on using HDFS in Spark Programming. Contains the following methods:

  `public <T> void saveToHDFS(JavaRDD<T> hdfsData, String path)` 
  `public JavaRDD<String> readHDFS(String filePath)`

• Main.java - Main class to test and run the classes in this project.