Creating standalone Mac App from JAR file

Question

I'm new to java but have built an application in eclipse which functions as intended. The end goal is to create a standalone .app with an icon for a user to click to run the application.

I've exported the project and created a standalone .jar file which when I double click, does not open. I get the error "The Java JAR file "File Name.jar" could not be launched. Check the Console for possible error messages." And when I look in the console, I don't see any error messages.

When I try to open my jar file in terminal with "java filename.jar", I get the error: "Error: could not find or load main class". However, when I launch the jar file in terminal, with "java -jar filename.jar" it opens fine.

I've packaged up the app using JarBundler, however the final .app file does not work either.

I don't know what to troubleshoot in order to get the .app file to open. Do I need my standalone executable jar to be able open without calling "java -jar", or is that unrelated? Why would my java file open with that but not without? Any guidance would be greatly appreciated.

Answer 1

You can use jpackage to create installable packages for Linux, Windows, and macOS. It's part of the JDK, so no need for extra tools.

• https://docs.oracle.com/en/java/javase/15/jpackage/preface.html
• https://www.baeldung.com/java14-jpackage