History of Java and the difference between Oracle JDK and OpenJDK

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1- A brief history of Java

Java was started by James Gosling and his colleagues at Sun Microsystems in 1991. It was originally from the idea of programming to control without relying on CPU used for electronic devices such as TVs, washing machines, microwaves, etc. Therefore, they embarked on building a fast, compact, efficient, device-independent language. Eventually, the "Oak" language was born, which was later renamed  Java.
James Gosling
At first, Java was named "Oak" because they are commonly grown in the US, Germany, Romania, and so on. They are also considered as a symbol of that country and a symbol of power. Addictionally, around the office of James Gosling were a lot of oak trees also planted.
Oak tree
In 1995, Oak was renamed Java because the name Oak was previously registered by a company called Oak Technologies. In the same year, the first version of Java was born. In order to get the first Java version, Sun Microsystems engineers had been working very hard for 4 years, from 1991 to 1995. During this time they worked day and night, and drank a lot of Coffee and Tea. The drinks helped them a lot, the cups appeared in their office all the time.

Why was the name Java chosen?

There are many suggested names for the members to select, such as Dynamic, Revolutionary, Silk, Jolt, DNA, ... However, they wanted a name reflecting the true nature of technology, which is revolutionary, highly dynamic, unique, and easy to pronounce, etc.

Java is an island in Indonesia, where the first coffee product was produced (called java coffee). Moreover, coffee had been attached to the engineers working for 4 years to create the first version of Java. That is the reason why most of the team members chose Java and as a result, the Java logo is a smoky, flavorful coffee cup.

According to James Gosling, Java is one of the top choices along with Silk. However, due to the uniqueness of  Java, most team members selected Java.

2- JVM and Slogan of Java

The biggest purpose of Java is how to write a program that can run on different platforms. Java's famous slogan is "Write Once and Run Anywhere - WORA".
Before Java was born, a program that was written and compiled into a machine code running on Windows operating systems would not be able to run on Linux operating systems because of a lot of differences.
Sun Microsystems engineers had created JVM (Java Virtual Machine) to install on different platforms such as  Windows, Linux, Mac, etc.
Java-written programs are compiled into Byte Code, a special code that can run in the JVM environment. JVM helps translate Byte Codes into the host machine's codes. This is the principle which explains why Java can run on different platforms.

3- What are JDK and JRE?

JRE

JRE is short for Java Runtime Environment, which includes JVM (Java Virtual Machine) and a number of Java libraries that support to execute programs written in the Java language.

JDK

JDK stands for Java Development Kit, which consists of 2 components, JRE and Java Development Tools.
JDK is necessary for programmers because Java Development Tools provides tools for Java application development, such as Javac which compile the developer's source codes into Byte Codes, etc. then uses  JRE to run the application during the development process.

4- OpenJDK vs Oracle JDK

The table below describes the history of different  Java versions.
Version Release
date
End of Free
Public Updates
Extended
Support Until
JDK Beta 1995 ? ?
JDK 1.0 January 1996 ? ?
JDK 1.1 February 1997 ? ?
J2SE 1.2 December 1998 ? ?
J2SE 1.3 May 2000 ? ?
J2SE 1.4 February 2002 October 2008 February 2013
J2SE 5.0 September 2004 November 2009 April 2015
Java SE 6 December 2006 April 2013 December 2018
Java SE 7 July 2011 April 2015 July 2022
Java SE 8 (LTS) March 2014 January 2019 for Oracle (commercial)
December 2020 for Oracle (personal use)
At least September 2023 for AdoptOpenJDK
At least June 2023 for Amazon Corretto
December 2030
Java SE 9 September 2017 March 2018 for OpenJDK N/A
Java SE 10 March 2018 September 2018 for OpenJDK N/A
Java SE 11 (LTS) September 2018 At least August 2024 for Amazon Corretto
September 2022 for AdoptOpenJDK
September 2026
Java SE 12 March 2019 September 2019 for OpenJDK N/A
Java SE 13 September 2019 March 2020 for OpenJDK N/A
Java SE 14 March 2020 September 2020 for OpenJDK N/A
Java SE 15 September 2020 March 2021 for OpenJDK N/A
Java SE 16 March 2021 September 2021 for OpenJDK N/A
Java SE 17 (LTS) September 2021 TBA TBA
In a major event in October 2009, Oracle purchased Sun Microsystem. Since then  Java officially changed its owner. Please pay full attention to before and after 2009.
From the first to the sixth Java versions were developed by Sun Microsystem, they opened Java source code for everyone in the world.
In July 2011, Oracle released Java 7. Two different JDK variants, Oracle JDK and OpenJDK were also available at the time when the source code of these two variants did not make too many differences, because they were both inherited from JDK 6.

OpenJDK

OpenJDK is opened source code, it is maintained and developed by Oracle, but allows communities and other companies to participate in this development, such as Red Hat, Azul Systems, IBM, Apple Inc, etc. OpenJDK is both a JDK product and a specification, any company or organization that wants to use OpenJDK to create a new variant must comply with those specifications.
OpenJDK is developed by Oracle and the community contributions. We sometimes have issues on its stability; however, based on user feedback, it will be upgraded to perform better. OpenJDK is regularly updated, around every 6 months.

Oracle JDK

Oracle JDK is maintained and developed by Oracle. It complies  with  OpenJDK specifications, but it is not opened source code. Oracle JDK is much better in terms of the  JVM responsiveness and productivity. It focuses more on the stability due to its importance to the corporate customers.

You might be asking the question, "What is a specification?". Let's see an example, an organization defines the size of a bicycle tire, which is a specification, and a manufacturer needs to comply with that regulation, whereas, the specification doesn't care how the manufacturer makes the tires.

OpenJDK was released under the "GPL v2" license, while Oracle JDK was released under the "Oracle Binary Code License Agreement".

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