Note: this post somehow related with this question; however, the error is different. So I am posting as another question.

• I want to try the new Project Loom feature defined in: JEP 428: Structured Concurrency (Incubator)

• I created a library project that uses class StructuredTaskScope, which can compile right.
  

• Then I created a test project to demonstrate the use of library project, which can compile right too.
  

• In pom.xml, both projects use:

   <plugin>
      <groupId>org.apache.maven.plugins</groupId>
      <artifactId>maven-compiler-plugin</artifactId>
      <version>3.10.1</version>
      <configuration>
          <release>19</release>
          <compilerArgs>
              <arg>--enable-preview</arg>
              <arg>--add-modules=jdk.incubator.concurrent</arg>
          </compilerArgs>
      </configuration>
  </plugin>     
  

• However, When i try to run the test project, it returns error below:

  C:\me\codes\com.tugalsan\tst\com.tugalsan.tst.thread>java -jar target/com.tugalsan.tst.thread-1.0-SNAPSHOT-jar-with-dependencies.jar --enable-preview --add-modules jdk.incubator.concurrent
  Exception in thread "main" java.lang.NoClassDefFoundError: jdk/incubator/concurrent/StructuredTaskScope
          at java.base/java.lang.ClassLoader.defineClass1(Native Method)
          at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1013)
          at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:150)
          at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:862)
          at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:760)
          at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:681)
          at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:639)
          at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
          at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
          at com.tugalsan.api.thread.server.TS_ThreadFetchAll.<init>(TS_ThreadFetchAll.java:44)
          at com.tugalsan.api.thread.server.TS_ThreadFetchAll.of(TS_ThreadFetchAll.java:85)
          at com.tugalsan.tst.thread.Main.main(Main.java:13)
  Caused by: java.lang.ClassNotFoundException: jdk.incubator.concurrent.StructuredTaskScope
          at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
          at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
          at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
          ... 12 more
  

I also tried adding '=' character, but no luck: java -jar target/com.tugalsan.tst.thread-1.0-SNAPSHOT-jar-with-dependencies.jar --enable-preview --add-modules=jdk.incubator.concurrent

CodePudding user response：

As Joachim Sauer answered:

Everything after the -jar filename.jar will be passed as an argument. Hence to run an app with jdk.incubator.concurrent, one should use below order:

java --enable-preview --add-modules jdk.incubator.concurrent -jar JARFILENAME.jar argument0 argument1 argument2...