Book Image

Apache Spark 2.x for Java Developers

By : Sourav Gulati, Sumit Kumar
Book Image

Apache Spark 2.x for Java Developers

By: Sourav Gulati, Sumit Kumar

Overview of this book

Apache Spark is the buzzword in the big data industry right now, especially with the increasing need for real-time streaming and data processing. While Spark is built on Scala, the Spark Java API exposes all the Spark features available in the Scala version for Java developers. This book will show you how you can implement various functionalities of the Apache Spark framework in Java, without stepping out of your comfort zone. The book starts with an introduction to the Apache Spark 2.x ecosystem, followed by explaining how to install and configure Spark, and refreshes the Java concepts that will be useful to you when consuming Apache Spark's APIs. You will explore RDD and its associated common Action and Transformation Java APIs, set up a production-like clustered environment, and work with Spark SQL. Moving on, you will perform near-real-time processing with Spark streaming, Machine Learning analytics with Spark MLlib, and graph processing with GraphX, all using various Java packages. By the end of the book, you will have a solid foundation in implementing components in the Spark framework in Java to build fast, real-time applications.
Table of Contents (19 chapters)
Title Page
About the Authors
About the Reviewer
Customer Feedback

Lambda expressions

Lambda expressions are the brand new feature of Java. Lambda expressions are introduced in Java 8 and it is a step towards facilitating functional programming in Java.

Lambda expressions help you to define a method without declaring it. So, you do not need a name for the method, return-type, and so on. Lambda expressions, like anonymous inner classes, provide the way to pass behaviors to functions. Lambda, however, is a much more concise way of writing the code.

For example, the preceding example of an anonymous inner class can be converted to Lambda as follows:

public class MyFilterImpl { 
   public static void main(String[] args) { 
      File dir = new File("src/main/java"); 
      dir.list((dirname,name)->name.endsWith("java")); //Lambda Expression 

Note that the signature of the Lambda expression is exactly matching the signature of the accept method in the FilenameFilter interface.


One of the huge differences between Lambda and anonymous inner classes...