What version of JRE should I use to run a Java 15 compiled program?

Question

I am new to Java Programming. Recently I created a JavaFX program using the latest JDK 15 (https://www.oracle.com/java/technologies/javase-downloads.html) and the latest JavaFX SDK 15 (https://openjfx.io/index.html). Suppose that I need to deploy the application (.jar) in someone else's computer.

• What is the version of JRE which should be in the client's PC? Or does he need to install complete JDK?
• My program contains VM options so that can I embed them within the .jar file?
• Are there specific JREs for version after Java 8? Or is the JRE coupled with the JDK itself?

Answer 1

From Java 9 onwards, Oracle no longer provides a JRE-only installation kit, either with the Oracle Java badge or the OpenJDK badge. That's why you can't find Java 15 JRE downloads on the Oracle and OpenJDK download sites.

You / they have three options:

1. They can download and install a JDK for Java 15. You or he will also need to deal with the JavaFX JAR and other 3rd-party JARs that your application uses.
2. You can use jlink (or similar) to turn your JAR file into an executable with an embedded (cut down) JRE. You then ship that executable rather than the JAR file.
3. You can recommend that they obtain Java from a 3rd party Java vendor that provides a JRE option for Java 15.

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My program contains VM options so that can I embed them within the .jar file?

I don't think you can do that. But it should be a simple matter to write a shell script or batch file which calls (for example) java with the required options.

If you use jlink you can embed JVM options in the executable; see How to set VM options for JLink launcher executable.

The jpackage tool may also be an option, though this is not a production feature until Java 16.