• Introduction
• Background
• Distributions
• Versions

Caveat: At the release of this wiki page, Java 15 is the current released Java Development Kit (JDK).

Introduction

Every project will require the use of at least one Java Development Kit (JDK). This is the source, root, or core of the code that will be used in each project. It may be a quick decision to just select the most recent JDK, though this might end in frustration and confusion during the build process. This wiki will review the different JDK versions and distributions. Yes, even distributions are different! Distributions are provided by various companies and may contain additional features from the root JDK. The wiki page objective is to remove any confusion about which version or distribution to use.

Background

Distribution

Various distributions from vendors existed prior to Oracle changing its licensing structure and were used for various reasons, such as using variation(s) of the Java Virtual Machine (JVM) for performance. So what does this mean for you as a developer for yourself or your company? Well we have good news about which JDK to choose. Free open source distributions exist for commercial use. These will be listed in Distributions.

• Oracle - JDK Licensing - FAQs
• Lakesidesoftware - Article - 2019
• Aspera - Article - 2019

Version

With the change of the licensing model Oracle also updated their release pipeline to include regular feature updates at a faster rate. The overall goal of the JDK development team is to move forward with the bigger Java Enhancement Proposals (JEPs) (Valhalla, Panama) by working out the foundational JEPs. Some smaller but related features that are foundational to the bigger JEPs are (Records, Sealed Classes) will be released in between the major features.

• All JEPs

Versions

Since each platform that Java works on is different the code; translation may leaves features out or may not be capable of being emulated from the desktop to mobile or web. Thus, if developing on a specific platform, you may not have much of a choice on which Java versions. As a developer you may also be faced with having to use multiple JDKs to support the features and/or debugging capabilities required by the project. Most of the versions listed will be Long Term Supported (LTS). Hot swapping code is a feature that allows one to compile and swap code during runtime debugging. This feature enhanced by using Dynamic Code Execution Virtual Machine (DCEVM). This is technically a separate distribution DCEVM. Some developers will use JDK 8 for language compatibility, JDK 11 for DCEVM and JDK 14 for packaging.

Note: LTS (Long Term Support)

Of these versions it is recommended to use LTS versions & distributions. This way any issues that arise in the JDK will be fixed or supported by the companies involved in the JDK maintenance.

Distributions

JDKs Distribution info can be found here sdkman.io - JDKs.