Graal is a separate JVM from the standard JDK version of Java. As such, not everything works the same!
The examples in this directory require use of GraalVM; they will probably not work in a standard JVM or JDK!!
Note that with Java 21, the Graal team dropped the previous "gu" installer in favor of using Maven/Gradle to add support for polyglot languages (e.g., ruby, python). This project has been updated; see the depenencies in the pom.xml file. For a more involved example, see https://github.com/graalvm/polglot-embedding-demo. For background on these changes, see https://medium.com/graalvm/truffle-unchained-13887b77b62c.