spring autowiring with unique beans: Spring expected single matching bean but found 2

I am trying to autowire some beans (for dependency injection) using Spring for a webapp. One controller bean contains another bean which in turn holds a hashmap of another set of beans. For now the map only has one entry. When i run in tomcat and call the service I get an error saying that the second bean (held in the controller) is not unique

No unique bean of type [com.hp.it.km.search.web.suggestion.SuggestionService] is defined: expected single matching bean but found 2: [suggestionService, SuggestionService]

I cannot see where I am defining the bean twice however am new to Spring and autowiring so I may be missing something fundamental. Source code for xml and 2 class listed below...

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"     xmlns:context="http://www.springframework.org/schema/context"     xmlns:mvc="http://www.springframework.org/schema/mvc"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="
    http://www.springframework.org/schema/beans     
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context 
    http://www.springframework.org/schema/context/spring-context-3.0.xsd
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc-3.0.xsd">

<context:component-scan base-package="com.hp.it.km.search.web.suggestion" />
<mvc:annotation-driven />
<context:annotation-config />

<bean id="SuggestionController" class="com.hp.it.km.search.web.suggestion.SuggestionController">
	<property name="service">
		<ref bean="SuggestionService" />
	</property>
</bean>

<bean id="SuggestionService" class="com.hp.it.km.search.web.suggestion.SuggestionService">
	<property name="indexSearchers"> 
		 <map>
    		<entry key="KMSearcher"> <ref bean="KMSearcherBean"></ref></entry>
		</map>
	</property>
</bean>

<bean id="KMSearcherBean" class="com.hp.it.km.search.web.suggestion.SuggestionIndexSearcher">
	  <constructor-arg index="0" value="KMSearcher" />
	  <constructor-arg index="1" value="C://dev//workspace//search-restful-webapp//src//main//resources//indexes//keyword" />
</bean>

The class asscoaites with the autowired controller and service bean are here...

@Controller
public class SuggestionController {
private SuggestionService service;

@Autowired
public void setService(SuggestionService service) {
	this.service = service;
}

public SuggestionService getService() {
	return service;
}

and...

@Component
public class SuggestionService {

private Map<String, IndexSearcher> indexSearchers = new HashMap<String,      IndexSearcher>();

@Autowired
public void setIndexSearchers(Map<String, IndexSearcher> indexSearchers) {
	this.indexSearchers = indexSearchers;
}

    public SuggestionService() {
	super(); }

Please Help!

The issue is because you have a bean of type SuggestionService created through @Component annotation and also through the XML config . As explained by JB Nizet, this will lead to the creation of a bean with name 'suggestionService' created via @Component and another with name 'SuggestionService' created through XML .

When you refer SuggestionService by @Autowired, in your controller, Spring autowires "by type" by default and find two beans of type 'SuggestionService'

You could do one of the following

1. Remove @Component from your Service and depend on mapping via XML - Easiest

2. Remove SuggestionService from XML and autowire the dependencies - use util:map to inject the indexSearchers map.

3. Use @Resource instead of @Autowired to pick the bean by its name .

    @Resource(name="suggestionService")
    private SuggestionService service;
   

or

    @Resource(name="SuggestionService")
    private SuggestionService service;

both should work.The third is a dirty fix and it's best to resolve the bean conflict through other ways.

If you have 2 beans of the same class autowired to one class you shoud use @Qualifier (Spring Autowiring @Qualifier example).

But it seems like your problem comes from incorrect Java Syntax.

Your object should start with lower case letter

SuggestionService suggestion;

Your setter should start with lower case as well and object name should be with Upper case

public void setSuggestion(final Suggestion suggestion) {
    this.suggestion = suggestion;
}

For me it was case of having two beans implementing the same interface. One was a fake ban for the sake of unit test which was conflicting with original bean. If we use

> @component("suggestionServicefake")

, it still references with suggestionService. So I removed @component and only used

> @Qualifier("suggestionServicefake")

which solved the problem

If I'm not mistaken, the default bean name of a bean declared with @Component is the name of its class its first letter in lower-case. This means that

@Component
public class SuggestionService {

declares a bean of type SuggestionService, and of name suggestionService. It's equivalent to

@Component("suggestionService")
public class SuggestionService {

or to

<bean id="suggestionService" .../>

You're redefining another bean of the same type, but with a different name, in the XML:

<bean id="SuggestionService" class="com.hp.it.km.search.web.suggestion.SuggestionService">
    ...
</bean>

So, either specify the name of the bean in the annotation to be SuggestionService, or use the ID suggestionService in the XML (don't forget to also modify the <ref> element, or to remove it, since it isn't needed). In this case, the XML definition will override the annotation definition.