Release 11 is still supported for several years, but users should consider upgrading to a newer branch. The most widely-used Long-term support (LTS) branches of OpenJDK are release 11 and release 17. Users who only want to run Java programs only require the JRE. The JRE is much less efficient at running Java files than applications because it must compile the source code first. It can also run Java files, but cannot convert these files into programs. The JRE interprets Java bytecode into lower-level code. It bundles the Java Virtual Machine (JVM) together with the Java Class Library (JCL) and other files.

JRE: The JRE executes Java code and compiled Java bytecode.

Some Java-dependent applications require the JDK because they convert Java Server pages into Java servlets and must compile them first. The JDK is necessary to create stand-alone Java executables. It also contains a development kit consisting of developer tools and a debugger. The JDK includes the Javac compiler for compiling Java programs into bytecode.

JDK: The JDK is primarily used by Java developers.

The JDK package includes the JRE, but the JRE can be downloaded as a stand-alone application. There are two main components to OpenJDK, the Java Developer Kit (JDK) and the Java Runtime Environment (JRE). With the exception of the licensing details, OpenJDK and Java SE are almost the same. OpenJDK is offered under the GNU General Public License (GPL) 2.0 license. OpenJDK is an alternative to the official Oracle Java implementation, which has a more restrictive license. Java is class-based and is regarded as fast, reliable, and secure. Java is a popular and versatile object-oriented programming language that is frequently used for business applications. OpenJDK is a free open-source version of the Java Platform, Standard Edition (Java SE). It also demonstrates how to configure OpenJDK and write a short test script to validate the installation.

This guide explains how to download and install OpenJDK on Ubuntu 22.04. OpenJDK is a free, open-source, production-ready implementation of Java based on Oracle’s commercial version of Java.

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