[HowTo] I have downloaded a program as a jar file - what now?

Difficulty: ★☆☆☆☆

What is a jar file

A jar is java package - a zip-compressed archive - including the code for a java application.

How can I start the application

The jar requires at least JRE (Java Runtime Environment) - some requires the full JDK (Java Development Kit). A JDK contains the corresponding JRE.

If in doubt of the actual requirements of the application - install the JDK.

To install the latest JRE

sudo pacman -Syu jre-openjdk

Or the complete environment

sudo pacman -Syu jdk-openjdk

Commandline

To run the application contained in the jar

java -jar java-app.jar

Create a script and a launcher

If you want to launch the program from your menu or the terminal - create a script and a launcher as follows.

  1. Create the bin folder

    mkdir ~/.local/bin
    
  2. Move the jar to the bin folder
    Assuming it is in Downloads

    mv ~/Downloads/java-app.jar ~/.local/bin
    
  3. Create the script
    Open your favorite text editor with a new file and save it as ~/.local/bin/java-app with below content - the “$@” ensures that any arguments to the script is passed on to the java-app.jar file

    #!/bin/sh
    java -jar ~/.local/bin/java-app.jar "$@"
    
  4. Make the script executable

    chmod +x ~/.local/bin/java-app
    
  5. Create the application folder

    mkdir -p ~/.local/share/applications
    
  6. Create the desktop launcher
    Use the text editor to create a new file and save it as ~/.local/share/applications/java-app.desktop with below content

    [Desktop Entry]
    Encoding=UTF-8
    Name=Some Java App
    Comment=Run the java-app.jar program
    GenericName=Some Java App
    Exec=~/.local/bin/java-app
    Terminal=false
    Type=Application
    Icon=java-app-icon
    Categories=Application;
    StartupWMClass=java-app
    StartupNotify=true
    

Conclusion

You are now be able to run Some Java App by providing the script name and any arguments for the java-app.jar and you can find it in the system’s menu tree.

4 Likes

Thank you for this great tutorial!

I could add additional step how to change current Java environment (granted you have more than one).

  1. Check available Java environments:
    archlinux-java status

Example output:

Available Java environments:
  java-11-openjdk
  java-14-openjdk
  java-8-openjdk/jre (default)
  1. Set new Java environment:
    sudo archlinux-java set java-11-openjdk

Result:

Available Java environments:
  java-11-openjdk (default)
  java-14-openjdk
  java-8-openjdk/jre
1 Like