package javax.jnlp is declared in module java.jnlp, which is not in the module graph

Question

I have a project that uses Java webstart technology. I decided to upgrade the Java version from 8 to 9. However, I faced the following error on compiling:

error: package javax.jnlp is not visible
import javax.jnlp.DownloadServiceListener;
        ^
(package javax.jnlp is declared in module java.jnlp, which is not in the module graph)

I tried to include C:\Program Files\Java\jdk-9\lib\javaws.jar to the classpath, but still the same issue remains.

Answer 1

It looks like java.jnlp is not resolved by default for code on the class path (much like Java EE modules). The solution is to add it explicitly with --add-modules java.jnlp (both javac and java accepts that parameter).

This option is discussed in JEP 261: Module System or in this blog post.

Answer 2

In IntelliJ IDEA: Add javaws.jar to Classpath(File -> Project Structure -> SDKs ->Class) C:\Program Files\Java\jdk-version\lib\javaws.jar