Jswap

Jswap allows you to quickly download and switch between different versions of the Java JDK via the command line. It works on Windows, Linux and macOS and does not require admin permissions.

Jswap uses the the Adoptium API to download the Eclipse Temurin distribution of OpenJDK.

Installation

Prebuilt binaries for Windows, Linux and macOS can be downloaded from the Releases page.

Linux and macOS

1. Download the tar.gz archive for your OS and architecture, then extract the archive you just downloaded into a folder that is in your PATH, such as /usr/local/bin or ~/.local/bin.
2. Append the following lines to the .bashrc file in your home directory (or .zshrc file if you are using zsh):

   export JAVA_HOME=~/.jswap/current-jdk
   export PATH=$JAVA_HOME/bin:$PATH

Windows

Simply download and run the .exe installer. This will set (and eventually override) the JAVA_HOME environment variable for te current user and add jswap, java and javac to the current user PATH.

Jswap can then be easily uninstalled from the "Add/Remove Programs" section in the Windows Control Panel.

The Unix way

Alternatively, if you have Bash installed on Windows, you can install Jswap in the same way you would install it on Linux or macOS. The only difference is that the Jswap Windows executable stores data in the LocalAppData folder rather than the home directory.

This will make Jswap available only in the Bash shell and will not touch the Windows environment variables.

1. Download the zip archive for Windows and extract it into a folder that is in your PATH, or into a new folder and then add it to you PATH.
2. Append the following lines to the .bashrc file in your home directory (create the file if it does not exists):

   export JAVA_HOME=$LOCALAPPDATA/Jswap/current-jdk
   export PATH=$JAVA_HOME/bin:$PATH

Usage

Download and install the latest available release of a given JDK major:

jswap get 21

Modify PATH and JAVA_HOME to use the latest installed release of a given major:

jswap set 21

List all the installed JDKs:

jswap ls

Run jswap --help for more information.

Build from sources

To build the Jswap executable from sources you need the following dependencies:

• Go
• Make
• Git

To build Jswap for your OS and architecture run this:

make

You can also target different platforms:

make linux-amd64 # Linux x64
make win-amd64 # Windows x64
make mac-amd64 # macOS with Intel CPU
make mac-arm64 # macOS with ARM CPU

The executables will be found in the build directory.

Windows installer

To build the Windows installer you need NSIS and the EnVar plugin for NSIS.

NSIS is also available on Linux and can be easily installed via apt on Ubuntu and Debian:

sudo apt install nsis

Place the EnVar plugin dll files in /usr/share/nsis/Plugins.

Run the following command to build the Jswap Windows installer:

make win-installer

Build using Docker

You can build Jswap and the Windows installer for any supported platform using Docker, without any other dependency.

First, build the jswap-builder Docker image:

docker build -t jswap-builder .

Run the following command to create a Docker container that builds Jswap and the Windows installer for all the supported platforms from the sources in the current directory:

docker run -v $PWD:/app --name jswap-builder jswap-builder

The jswap-builder image runs the Make target all by default. If you want to run a different Make target you can pass it as a command to docker run. For example, if you want to build only the Windows installer run this:

docker run -v $PWD:/app --name jswap-builder jswap-builder win-installer

For subsequent builds you can reuse the previously created container to improve build times:

docker start -a jswap-builder