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mavenconcurrencyjava-19

How can I run JDK 19 with Structured Concurrency? (ERROR: java.lang.NoClassDefFoundError: jdk/incubator/concurrent/StructuredTaskScope)

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

Solution

  • 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...