Overview

cjdk (for “cached JDK”) is a Python package and command-line tool to download and run JDK (Java Development Kit) or JRE (Java Runtime Environment) distributions.

Previously used JDKs are kept in the user’s cache directory, so that future invocations do not require a download.

Possible use cases include:

• Installing exact JDK versions for reproducible testing

• Working with multiple versions of JDKs

• Deploying tools that require Java

Using the command-line interface of cjdk, you can run Java programs using a one-liner, without having to worry about whether the user has installed a new enough Java runtime and set JAVA_HOME and PATH to appropriate values.

For example, the following command will run Checkstyle using Temurin JRE 17 (which will be downloaded if this is the first time it is requested):

cjdk --jdk=temurin-jre:17 exec java -jar checkstyle-10.3-all.jar -c style.xml MyApp.java

cjdk is distrubuted under the MIT license.

Acknowledgments

cjdk was inspired by Coursier’s java command, and uses Coursier’s JDK index.