The article represents different set of information that Java developers (working on 5, 6, 7 versions) may need to learn prior to getting started and make best use of Java 8 features. In case, you feel there are other topics that developers need to look beforehand, please suggest.

Following are different concepts which Java developers working with earlier versions of Java need to understand very clearly in order to get started comfortably with Java 8 features.

Functional programming concepts

Learning functional programming concepts would help you learn Java 8 flagship feature such as Lambda expressions. In short, Lambda expressions helps you treat functionality (represented as code) as data which you could pass as parameters to other functions. Following are some of the great pages on functional programming that would help you understand the functional programming and underlying concepts in an easy manner.

Anonymous inner classes and Single Abstract Method (SAM) Interfaces/Classes

Have you come across interfaces such as following: java.lang.Runnable (run), java.awt.event.ActionListener, java.util.Comparator (compare), java.util.concurrent.Callable (call) etc. The common between all these interfaces is presence of just one method. One of the ways in which these single methods interfaces are used is anonymous inner class such as following:

The above concepts would help you learn and code Lambda expressions which are also based on SAM interface concept. You may want to check out following pages to check out code samples in relation with Lambda expressions.

http://zeroturnaround.com/rebellabs/java-8-the-first-taste-of-lambdas/

Modular Java & Project Jigsaw

A high level understanding on Project Jigsaw and Modular Java platform (targeted for Java 9 or ahead) would be helpful in understanding the concepts behind Compact Profiles, the unique feature of Java 8 release.

Oracle Nashorn – Javascript Engine for JVM

One of the primary object behind the Nashorn project is to open up JVM to languages (such as Javascript) other than Java and allow developers to access of the benefits of Java including large set of libraries, and great support from open source Java community. You may want to check out https://jcp.org/en/jsr/detail?id=292 to know greater details around Nashorn engine. It would be good to understand the Rhino which was shipped with Java 6. You may also want to check out similar Javascript engine such as Google V8 which allows C++ applications to expose its objects and functions to Javascript code.

Functional Style Operations such as Map-Reduce Transformations

New classes such as Collector have been added in the java.util.stream package that provides a Stream API to provide functional styled operations such as map-reduce transformations. To be able to use it, one needs to understand the concepts around map-reduce transformations and the real-world use-cases when they would needed to be used.

Security Concepts

Given that application security has caught up big time with businesses, it is time that Java developers understand various nuances of security that they may need to handle with Java 8 security features. Following topics would be good to understand:

Algorithm such as Authenticated Encryption with Associated Data (AEAD) (http://tools.ietf.org/pdf/rfc5116.pdf)

Encryption concepts including keystores, message digests, kerberos

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