Java Community | Help. Code. Learn.•2w ago

Dynamic Maven Artifact using ASM - Module not found

I generate a maven artifact dynamicly. In order to modularize the Artifact I need to generate a module-info.class. This is my code to generate the bytecode:

public class BytecodeHelper {
    public static final String MODULE_INFO = "module-info";

    public static byte[] buildModuleClass(String moduleName, String exportPackage) throws IOException {
        ClassWriter classWriter = new ClassWriter(0);
        classWriter.visit(Opcodes.V9, Opcodes.ACC_MODULE, MODULE_INFO, null, null, null);
        ModuleVisitor mv = classWriter.visitModule(moduleName, 0, null);
        mv.visitExport(exportPackage, 0);
        mv.visitEnd();
        classWriter.visitEnd();
        return classWriter.toByteArray();
    }
}

public class BytecodeHelper {
    public static final String MODULE_INFO = "module-info";

    public static byte[] buildModuleClass(String moduleName, String exportPackage) throws IOException {
        ClassWriter classWriter = new ClassWriter(0);
        classWriter.visit(Opcodes.V9, Opcodes.ACC_MODULE, MODULE_INFO, null, null, null);
        ModuleVisitor mv = classWriter.visitModule(moduleName, 0, null);
        mv.visitExport(exportPackage, 0);
        mv.visitEnd();
        classWriter.visitEnd();
        return classWriter.toByteArray();
    }
}

Unfortunately maven is unhappy with the module-info.class. Message is:

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  12.795 s (Wall Clock)
[INFO] Finished at: 2025-11-18T18:57:23+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.11.0:compile (default-compile) on project de.xx: Compilation failure
[ERROR] /home/xx/workspace/xx/de.xx/src/main/java/module-info.java:[17,18] module not found: xxdb

[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  12.795 s (Wall Clock)
[INFO] Finished at: 2025-11-18T18:57:23+01:00
[INFO] ------------------------------------------------------------------------
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:3.11.0:compile (default-compile) on project de.xx: Compilation failure
[ERROR] /home/xx/workspace/xx/de.xx/src/main/java/module-info.java:[17,18] module not found: xxdb

15 Replies

JavaBot•2w ago

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dan1st•2w ago

Can you elaborate on what you mean with creating an artifact dynamically? When do you create it? How do you add the created artifact to the build? Can you run the (failing) Maven build with -X and show the output? Can you show the final module-info.class? btw the Class-File API exists as well, just saying

Peter RaderOP•2w ago

Oh just create a jar-file having the bytecodes that has been generated from the buildModuleClass-call in the root-file named "module-info.class". The rest of the jar could remain empty. Then install the jar using

mvn install:install-file -Dfile=<path-to-file> -DgroupId=<group-id> -DartifactId=<artifact-id> -Dversion=<version> -Dpackaging=<packaging>

I create the jar on demand.

dan1st•2w ago

so the JAR is created in a distinct Maven build Can you run jar tf <jarfile>.jar on the JAR in the local Maven repo? And then extract it and run javap module-info.class

Peter RaderOP•2w ago

grim@ubuntudev:~/.m2/repository/de/xxx/xx/2025.11.18.17.34.40$ jar tf rm-2025.11.18.17.34.40.jar 
META-INF/
META-INF/maven/
META-INF/maven/de.xxx/
META-INF/maven/de.xxx/rm/
META-INF/maven/de.xxx/rm/pom.xml
META-INF/MANIFEST.MF
de/
de/xxx/
de/xxx/xx
module-info.class

grim@ubuntudev:~/.m2/repository/de/xxx/xx/2025.11.18.17.34.40$ jar tf rm-2025.11.18.17.34.40.jar 
META-INF/
META-INF/maven/
META-INF/maven/de.xxx/
META-INF/maven/de.xxx/rm/
META-INF/maven/de.xxx/rm/pom.xml
META-INF/MANIFEST.MF
de/
de/xxx/
de/xxx/xx
module-info.class

grim@ubuntudev:~/.m2/repository/de/xxx/rm/2025.11.18.17.34.40$ javap module-info.class 
module xxdb {
  exports de.xxx;
}
grim@ubuntudev:~/.m2/repository/de/xxx/rm/2025.11.18.17.34.40$

grim@ubuntudev:~/.m2/repository/de/xxx/rm/2025.11.18.17.34.40$ javap module-info.class 
module xxdb {
  exports de.xxx;
}
grim@ubuntudev:~/.m2/repository/de/xxx/rm/2025.11.18.17.34.40$

dan1st•2w ago

What exact files are in the repo for that version? and what is the output of the failing Maven build with -X? btw you censored the package name here but not in the jar tf output if you want to edit it

Peter RaderOP•2w ago

By the way, other module-info.class show this structure in eclipse:

Peter RaderOP•2w ago

I may miss the "module packages:" scope....

dan1st•2w ago

hm? oh right

Peter RaderOP•2w ago

As you can see in the class-file-editor, the module-name is mentioned twice. In the first and last line. Hm, the ModuleVisitor have a method "visitPackage". I think I need to call it. I dont know how to write a unit test for that!

dan1st•2w ago

https://docs.oracle.com/javase/specs/jvms/se25/html/jvms-4.html#jvms-4.7.26 It's just a class file attribute

The ModulePackages attribute is a variable-length attribute in the attributes table of a ClassFile structure (§4.1). The ModulePackages attribute indicates all the packages of a module that are exported or opened by the Module attribute, as well as all the packages of the service implementations recorded in the Module attribute. The ModulePackages attribute may also indicate packages in the module that are neither exported nor opened nor contain service implementations. There may be at most one ModulePackages attribute in the attributes table of a ClassFile structure.

but first try using it with the javac/java command line and see whether that allows using your module and then check the Maven build with the -X argument which includes more information on the compilation I wouldn't be surprised if a missing POM in the local repo causes the issue

Peter RaderOP•2w ago

modules have no package-declaration. Since the ModuleVisitor have such method, I think it is reused for the "module packages:" scope.

dan1st•2w ago

they have a list of opened and exported packages So in your case, it would include de.xxx btw you can also use javap -v

Classfile /tmp/module-info.class
  Last modified 18 Nov 2025; size 148 bytes
  SHA-256 checksum 305a95e648ea4c504aae7bedf34b4a5cc9f5ad212ac3ac02b35db3f3f0b6374c
  Compiled from "module-info.java"
module Test
  minor version: 0
  major version: 69
  flags: (0x8000) ACC_MODULE
  this_class: #1                          // module-info
  super_class: #0
  interfaces: 0, fields: 0, methods: 0, attributes: 2
Constant pool:
   #1 = Class              #2             // "module-info"
   #2 = Utf8               module-info
   #3 = Utf8               SourceFile
   #4 = Utf8               module-info.java
   #5 = Utf8               Module
   #6 = Unknown            #7             // Test
   #7 = Utf8               Test
   #8 = Unknown            #9             // "java.base"
   #9 = Utf8               java.base
  #10 = Utf8               25
{
}
SourceFile: "module-info.java"
Module:
  #6,0                                    // Test
  #0
  1                                       // requires
    #8,8000                                 // "java.base" ACC_MANDATED
    #10                                     // 25
  0                                       // exports
  0                                       // opens
  0                                       // uses
  0                                       // provides

Classfile /tmp/module-info.class
  Last modified 18 Nov 2025; size 148 bytes
  SHA-256 checksum 305a95e648ea4c504aae7bedf34b4a5cc9f5ad212ac3ac02b35db3f3f0b6374c
  Compiled from "module-info.java"
module Test
  minor version: 0
  major version: 69
  flags: (0x8000) ACC_MODULE
  this_class: #1                          // module-info
  super_class: #0
  interfaces: 0, fields: 0, methods: 0, attributes: 2
Constant pool:
   #1 = Class              #2             // "module-info"
   #2 = Utf8               module-info
   #3 = Utf8               SourceFile
   #4 = Utf8               module-info.java
   #5 = Utf8               Module
   #6 = Unknown            #7             // Test
   #7 = Utf8               Test
   #8 = Unknown            #9             // "java.base"
   #9 = Utf8               java.base
  #10 = Utf8               25
{
}
SourceFile: "module-info.java"
Module:
  #6,0                                    // Test
  #0
  1                                       // requires
    #8,8000                                 // "java.base" ACC_MANDATED
    #10                                     // 25
  0                                       // exports
  0                                       // opens
  0                                       // uses
  0                                       // provides

Peter RaderOP•2w ago

Yeeees, solved! The correct implementation is:

public class BytecodeHelper {
    public static final String MODULE_INFO = "module-info";

    public static byte[] buildModuleClass(String moduleName, String exportPackage) throws IOException {
        ClassWriter classWriter = new ClassWriter(0);
        classWriter.visit(Opcodes.V9, Opcodes.ACC_MODULE, MODULE_INFO, null, null, null);
        ModuleVisitor mv = classWriter.visitModule(moduleName, 0, null);
        mv.visitExport(exportPackage, 0);
        mv.visitEnd();
        mv.visitPackage(moduleName);
        mv.visitEnd();
        classWriter.visitEnd();
        return classWriter.toByteArray();
    }
}

public class BytecodeHelper {
    public static final String MODULE_INFO = "module-info";

    public static byte[] buildModuleClass(String moduleName, String exportPackage) throws IOException {
        ClassWriter classWriter = new ClassWriter(0);
        classWriter.visit(Opcodes.V9, Opcodes.ACC_MODULE, MODULE_INFO, null, null, null);
        ModuleVisitor mv = classWriter.visitModule(moduleName, 0, null);
        mv.visitExport(exportPackage, 0);
        mv.visitEnd();
        mv.visitPackage(moduleName);
        mv.visitEnd();
        classWriter.visitEnd();
        return classWriter.toByteArray();
    }
}

Works like a charm!

JavaBot•2w ago

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Dynamic Maven Artifact using ASM - Module not found

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