Setup Java on WSL

Motivation

Refer to

Compiling Java code on Windows is 30% slower than on Linux

Updated Jul 26, 2021

and Java in Visual Studio Code and see the reason I choose WSL instead of Windows.

As required by the course, I will install Java 8., which is a LTS version.

There are many distributed versions of JDK. For convenience, I will choose to install directly from apt

Steps

(Optional) Ensures that you have the latest packages in WSL


sudo apt update && sudo apt upgrade

Verifying the availability of OpenJDK


apt-cache search openjdk-8 | grep openjdk-8

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Note jre is short for Java Runtime Environment, while jdk is for Java Development Kit.

Install OpenJDK 8


sudo apt install openjdk-8-jdk

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This command line will also install openjdk-8-jre automatically. So no bother to do it manually.

Verify the installation


java -version

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If you are installing Java 9+, java --version also works

If something goes wrong, use which java to determine if you are using the java just installed, or you are actually using other version installed previously (as below):

Write the following lines into ~/.bashrc to prepend the Java of desired version to PATH.


export JAVA_HOME="/usr/lib/jvm/java-8-openjdk-amd64/"
export PATH="$JAVA_HOME/bin:$PATH"

Don’t forget to run source ~/.bashrc to activate the added setting.

(Optional) Configure runtime version and path

In VScode, use Ctrl+Shift+P to open the Command Palette, search for Preference: Open Remote Settings (JSON) (WSL) and append the configuration below


{
    // other configurations
    ...,
    "java.configuration.runtimes": [
        {
            "name": "JavaSE-1.8",
            "path": "/usr/lib/jvm/java-8-openjdk-amd64",
            "default": true
        },
        {
            "name": "JavaSE-11",
            "path": "/usr/lib/jvm/java-11-openjdk-amd64",
        },
        {
            "name": "JavaSE-13",
            "path": "/usr/lib/jvm/java-13-openjdk-amd64",
        },
    ]
}

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You can set one of them to default by adding "default": true to the entry. To see which JDKs are used for your projects, you can trigger the command Java: Configure Java Runtime in Command Palette (Ctrl+Shift+P).

Done 👏

Use jenv to manage java version

Setup Java on windows


winget search jdk
winget install Oracle.JDK.21

Download Maven here, e.g., apache-maven-3.9.6-bin.zip

Maven – Download Apache Maven

Apache Maven 3.9.6 is the latest release: it is the recommended version for all users.

https://maven.apache.org/download.cgi

unzip the zip file, add /bin to environment variables.

Reference

code.visualstudio.com

https://code.visualstudio.com/docs/languages/java

How to Install OpenJDK 8 on Ubuntu 22.04 or 20.04 - LinuxCapable

Learn how to install OpenJDK 8 on Ubuntu 22.04 or the older stable release of Ubuntu 20.04 with step-by-step instructions.

https://www.linuxcapable.com/how-to-install-openjdk-8-on-ubuntu-linux/

A Brief Guide on Setting Up Java with WSL and VSCode - Binghuan's Blog

Recently I had the chance to set up the whole dev environment on a 2018 Surface Pro. So far I really love it! Smaller size, touch screen, and keyboard (oh, so much better than any Apple keyboard)! ...

https://estepona.github.io/2021/08/25/a-brief-guide-on-setting-up-java-with-wsl-and-vscode/