How to autowire an interface with multiple implementations

Question

I have an interface with 3 public methods

public interface IUtil {
//public methods
}

I implement 2 of the methods in one abstract class:

public abstract class PasswordUtil implements IUtil {

//implemented methods
}

and another in other class

public abstract class EmailUtil implements IUtil  {
}

Now I want to autowire the interface so that I can have access to two implemented classes in My DAO class and DAO class is in another package.

    public  class RegistrationDAO  implements IRegistrationDAO {
        @Autowired
        IUtil util;
        @Autowired
        SessionFactory sessionFactory;
            } 

The error I get while executing is :Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [in.amruth.xplore.utility.IUtil] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}

Exception Stack Trace:

    org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'xploreController': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.service.IRegistrationService in.amruth.xplore.controller.XploreController.iregistrationservice; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'registrationservice': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.dao.IRegistrationDAO in.amruth.xplore.service.RegistrationService.iregistrationDAO; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'iregistrationDAO': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.utility.IUtil in.amruth.xplore.dao.RegistrationDAO.util; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [in.amruth.xplore.utility.IUtil] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:700)
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:760)
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:482)
    at org.springframework.web.context.ContextLoader.configureAndRefreshWebApplicationContext(ContextLoader.java:403)
    at org.springframework.web.context.ContextLoader.initWebApplicationContext(ContextLoader.java:306)
    at org.springframework.web.context.ContextLoaderListener.contextInitialized(ContextLoaderListener.java:106)
    at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:4939)
    at org.apache.catalina.core.StandardContext.startInternal(StandardContext.java:5434)
    at org.apache.catalina.util.LifecycleBase.start(LifecycleBase.java:150)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1559)
    at org.apache.catalina.core.ContainerBase$StartChild.call(ContainerBase.java:1549)
    at java.util.concurrent.FutureTask.run(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.service.IRegistrationService in.amruth.xplore.controller.XploreController.iregistrationservice; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'registrationservice': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.dao.IRegistrationDAO in.amruth.xplore.service.RegistrationService.iregistrationDAO; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'iregistrationDAO': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.utility.IUtil in.amruth.xplore.dao.RegistrationDAO.util; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [in.amruth.xplore.utility.IUtil] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
    ... 22 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'registrationservice': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.dao.IRegistrationDAO in.amruth.xplore.service.RegistrationService.iregistrationDAO; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'iregistrationDAO': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.utility.IUtil in.amruth.xplore.dao.RegistrationDAO.util; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [in.amruth.xplore.utility.IUtil] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1014)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:957)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:855)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
    ... 24 more
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.dao.IRegistrationDAO in.amruth.xplore.service.RegistrationService.iregistrationDAO; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'iregistrationDAO': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.utility.IUtil in.amruth.xplore.dao.RegistrationDAO.util; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [in.amruth.xplore.utility.IUtil] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
    ... 35 more
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'iregistrationDAO': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.utility.IUtil in.amruth.xplore.dao.RegistrationDAO.util; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [in.amruth.xplore.utility.IUtil] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:292)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1185)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:537)
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:475)
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:304)
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:300)
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:195)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.findAutowireCandidates(DefaultListableBeanFactory.java:1014)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:957)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:855)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
    ... 37 more
Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: in.amruth.xplore.utility.IUtil in.amruth.xplore.dao.RegistrationDAO.util; nested exception is org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [in.amruth.xplore.utility.IUtil] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:508)
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:289)
    ... 48 more
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type [in.amruth.xplore.utility.IUtil] found for dependency: expected at least 1 bean which qualifies as autowire candidate for this dependency. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(DefaultListableBeanFactory.java:1100)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:960)
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:855)
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:480)
    ... 50 more

Answer 1

Your problem isn't that you have two implementations, your problem is you have none.

You only have abstract implementations which can't get instantiated, and therefore can't get injected anywhere.

Answer 2

As some comments has pointed out, you can't instantiate an abstract class for injection. When the target of your autowiring can resolve to multiple instance, you need to give hint with qualifier.

Example :

public  class RegistrationDAO  implements IRegistrationDAO {
    @Autowired
    @Qualifier("email")
    IUtil util;
    @Autowired
    SessionFactory sessionFactory;
} 

Where your beans.xml has the qualifier for those bean instances:

<beans>
    <bean class="PasswordUtil">
        <qualifier value="password" />
    </bean>
    <bean class="EmailUtil">
        <qualifier value="email" />
    </bean>
</beans>

See Spring 3.2.2 Reference manual chapter 5.9.3