Can Spring instantiate a static nested class?

[Andrew Swan]

I'm trying to instantiate a static nested class using a ClassPathXmlApplicationContext, but I get a ClassNotFoundException. Here's my config file:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN"
  "http://www.springframework.org/dtd/spring-beans.dtd">
<beans>
  <bean id="inner" class="test.Main.Inner"/>
</beans>

And here's my Java code:

package test;

import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {
  
  public static void main(String[] args) {
    new ClassPathXmlApplicationContext("test/my-config.xml");
  }
  
  public static class Inner {}
}

And here's the error:

17/07/2007 15:34:11 org.springframework.context.support.AbstractApplicationContext refresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@cdedfd: display name [org.springframework.context.support.ClassPathXmlApplicationContext@cdedfd]; startup date [Tue Jul 17 15:34:11 EST 2007]; root of context hierarchy
17/07/2007 15:34:11 org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [test/my-config.xml]
17/07/2007 15:34:12 org.springframework.context.support.AbstractApplicationContext refresh
INFO: Bean factory for application context [org.springframework.context.support.ClassPathXmlApplicationContext@cdedfd]: org.springframework.beans.factory.support.DefaultListableBeanFactory@1bc82e7
17/07/2007 15:34:12 org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1bc82e7: defining beans [inner]; root of factory hierarchy
17/07/2007 15:34:12 org.springframework.beans.factory.support.DefaultSingletonBeanRegistry destroySingletons
INFO: Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@1bc82e7: defining beans [inner]; root of factory hierarchy
Exception in thread "main" org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [test.Main.Inner] for bean with name 'inner' defined in class path resource [test/my-config.xml]; nested exception is java.lang.ClassNotFoundException: test.Main.Inner
Caused by: java.lang.ClassNotFoundException: test.Main.Inner
	at java.net.URLClassLoader$1.run(URLClassLoader.java:200)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
	at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:268)
	at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
	at org.springframework.util.ClassUtils.forName(ClassUtils.java:201)
	at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:325)
	at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1033)
	at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:274)
	at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:360)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:91)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:75)
	at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:65)
	at test.Main.main(Main.java:19)

Is this a bug or a feature?

I'm using Spring 2.0.4, FWIW.

Thanks for any help.

[Andreas Senft]

Try "test.Main$Inner".

Regards,
Andreas

[Andrew Swan]

Aha! That worked - thank you very much.

Is this in the Spring docs or did you just know it?

[Andreas Senft]

Aha! That worked - thank you very much.

You're welcome.

Is this in the Spring docs or did you just know it?

It is the standard java naming. If you compile your class you will notice that you will have a Main.class and a Main$Inner.class. I think I also read about that naming strategy somewhere but regrettably I cannot rmember where.
Anyway, glad it works for you.

Regards,
Andreas

[Andrew Swan]

It is the standard java naming.

Looking into this further, it seems you have to refer to the class as test.Main$Inner if you call Class.forName(String), which I guess is what the Spring XML bean factory does. However from within Java code, the class would be referred to as test.Main.Inner (this is also what you get in Eclipse if you right-click on the class and choose "Copy Qualified Name").

Anyway, thanks again for the learning experience.

[Rick Evans]

Is this in the Spring docs or did you just know it?

It is in the Spring docs, mentioned here in the sidebar entitled 'Inner class names'.

Cheers
Rick

[Jörg Heinicke]

It is in the Spring docs, mentioned here in the sidebar entitled 'Inner class names'.

Feels good, Rick, doesn't it?

Jörg