How to deal with LinkageErrors in Java?

by

LinkageError is what you’ll get in a classic case where you have a class C loaded by more than one classloader and those classes are being used together in the same code (compared, cast, etc). It doesn’t matter if it is the same Class name or even if it’s loaded from the identical jar – a Class from one classloader is always treated as a different Class if loaded from another classloader.

The message (which has improved a lot over the years) says:

Exception in thread "AWT-EventQueue-0" java.lang.LinkageError: 
loader constraint violation in interface itable initialization: 
when resolving method "org.apache.batik.dom.svg.SVGOMDocument.createAttribute(Ljava/lang/String;)Lorg/w3c/dom/Attr;" 
the class loader (instance of org/java/plugin/standard/StandardPluginClassLoader) 
of the current class, org/apache/batik/dom/svg/SVGOMDocument, 
and the class loader (instance of ) for interface org/w3c/dom/Document 
have different Class objects for the type org/w3c/dom/Attr used in the signature

So, here the problem is in resolving the SVGOMDocument.createAttribute() method, which uses org.w3c.dom.Attr (part of the standard DOM library). But, the version of Attr loaded with Batik was loaded from a different classloader than the instance of Attr you’re passing to the method.

You’ll see that Batik’s version seems to be loaded from the Java plugin. And yours is being loaded from ” “, which is most likely one of the built-in JVM loaders (boot classpath, ESOM, or classpath).

The three prominent classloader models are:

  • delegation (the default in the JDK – ask parent, then me)
  • post-delegation (common in plugins, servlets, and places where you want isolation – ask me, then parent)
  • sibling (common in dependency models like OSGi, Eclipse, etc)

I don’t know what delegation strategy the JPF classloader uses, but the key is that you want one version of the dom library to be loaded and everyone to source that class from the same location. That may mean removing it from the classpath and loading as a plugin, or preventing Batik from loading it, or something else.

More Related Contents:

  1. Java using much more memory than heap size (or size correctly Docker memory limit)
  2. Unloading classes in java?
  3. Scanning Java annotations at runtime
  4. Find where java class is loaded from
  5. Run a Java Application as a Service on Linux
  6. What does JVM flag CMSClassUnloadingEnabled actually do?
  7. Docker: Combine multiple images
  8. Classpath does not work under linux
  9. How can I list all classes loaded in a specific class loader
  10. How to download older google play services?
  11. Strange behavior of Class.getResource() and ClassLoader.getResource() in executable jar
  12. Distinguishing between Java threads and OS threads?
  13. Running a JAR file without directly calling `java`
  14. Class.forName() vs ClassLoader.loadClass() – which to use for dynamic loading? [duplicate]
  15. How to compile dynamic library for a JNI application on linux?
  16. JAVA_HOME and PATH are set but java -version still shows the old one
  17. Preloading java classes/libraries at jar startup?
  18. Replacement System Classloader for Classes In Jars containing Jars
  19. Change file owner group under Linux with java.nio.Files
  20. ClassCastException because of classloaders?
  21. How to use ClassLoader.getResources() correctly? [duplicate]
  22. How to open a command terminal in Linux?
  23. How can I make this JButton visible? When I have progressive scan background JWindow()?
  24. How to increase maximum number of JVM threads (Linux 64bit)
  25. Static references are cleared–does Android unload classes at runtime if unused?
  26. How to find a Java thread running on Linux with ps -axl?
  27. How to replace classes in a running application in java ?
  28. Java is installed, in listing, but execution produces “./java: No such file or directory”
  29. problems with java3D lib configuration
  30. Why Maven uses JDK 1.6 but my java -version is 1.7

Leave a Comment