Can java web start run on a device without JRE?

Question

I have been learning about Java web start and got interested in its features. But can my Java app downloaded and run from browser run on a device without a JRE(Java environment) installed?

I have tried download a sample jar from browser with Java web start but my app can't run.

Second question: Is there a feature in Java web start to check for an installed JRE and automatically setup the environment?

Answer 1

If "setup" refers to checking if a runtime is installed - that feature cannot of course be part of the Java runtime - that would turn it into a chicken-egg type of situation. At best an existing runtime will be able to detect that it is outdated.

But Oracle provides the Java Deployment Toolkit which is based on javascript:

http://www.java.com/en/download/faq/deployment_toolkit.xml

http://docs.oracle.com/javase/tutorial/deployment/deploymentInDepth/depltoolkit_index.html

JavaFX 2 provides ant tasks to automate those things away:

http://docs.oracle.com/javafx/2/deployment/deployment_toolkit.htm#BABJHEJA

Answer 2

a JRE is required on the client to run your java Web Start application as it is downloaded and executed localy and all Java applications need an installed JRE.

Java Web Start provides the option to declare a JRE (with version number) and download it if it is not installed. (But I never used it so I can't tell you how to set this up) found on wikipedia.

Answer 3

Java Webstart (JavaWS) is part of the Java Runtime Environment (JRE) http://www.java.com/en/download/faq/java_webstart.xml

An installed JRE is - as far as I know - required to run JavaWS applications.

I'm not aware of any method which would facilitate an automatic download/install of the current JRE. However, JavaWS allows you to enforce the use of a specific JRE version.

Answer 4

You cannot do such a things with applet/jnlp, but you can package your jar into an application package: http://docs.oracle.com/javafx/2/deployment/self-contained-packaging.htm