Argthtjtr

Assume I have the classes A,B,C,D,E:

@Component

public class A {

}



@Component

public class B {

}



@Component

public class D {

}



@Component

public class E {

}



public class C {

private List myList;



public List getMyList() {

    return myList;

}



public void setMyList(List myList) {

    this.myList = myList;

}

}

This is my application context:

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:context="http://www.springframework.org/schema/context"

xmlns:util="http://www.springframework.org/schema/util"

xsi:schemaLocation="http://www.springframework.org/schema/beans 

http://www.springframework.org/schema/beans/spring-beans.xsd

    http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd

    http://www.springframework.org/schema/util http://www.springframework.org/schema/util/spring-util-3.2.xsd">





    <util:list id="myList1">

        <ref bean="a"/>

        <ref bean="b"/>

    </util:list>



    <util:list id="myList2">

        <ref bean="d"/>

        <ref bean="e"/>

    </util:list>



    <bean id="myFirstC" class="com.app.C">

        <property name="myList" ref="myList1"></property>

    </bean>



    <bean id="mySecondC" class="com.app.C">

        <property name="myList" ref="myList2"></property>

    </bean>



    <context:component-scan base-package="com.app"></context:component-scan>

    </beans>

Is it possible to create the beans "myFirstC" and "mySecondC" using annotations inside C class? I have tried to autowire the lists inside the C class and then use @Bean annotation to create beans and set the lists, but get errors.

So, I tried to do it in this way:

@Component

@Configuration

public class C {



private List myList;



@Autowired

@Qualifier("myList1")

private List myList1;



@Autowired

@Qualifier("myList2")

private List myList2;



@Bean

public C getNewCBean1() {

    C c = new C();

    c.setMyList(myList1);

    return c;

}



@Bean

public C getNewCBean2() {

    C c = new C();

    c.setMyList(myList2);

    return c;

}

But get error like this:

Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'c': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.util.List com.app.C.myList1; nested exception is org.springframework.beans.FatalBeanException: No element type declared for collection [java.util.List]

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:288)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1116)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)

    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)

    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:295)

    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:223)

    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:292)

    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:194)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:626)

    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)

    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)

    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)

    at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)

    at com.app.Start.main(Start.java:9)

Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.util.List com.app.C.myList1; nested exception is org.springframework.beans.FatalBeanException: No element type declared for collection [java.util.List]

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:514)

    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:87)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:285)

    ... 13 more

Caused by: org.springframework.beans.FatalBeanException: No element type declared for collection [java.util.List]

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:807)

    at org.springframework.beans.factory.support.DefaultListableBeanFactory.resolveDependency(DefaultListableBeanFactory.java:768)

    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:486)

    ... 15 more

I could not find a solution to this in documentations and forums. Any help will be appreciated. Thank you

Your Java code doesn't do the same thing as your xml code at all:

<util:list id="myList1">

    <ref bean="a"/>

    <ref bean="b"/>

</util:list>



<util:list id="myList2">

    <ref bean="d"/>

    <ref bean="e"/>

</util:list>



<bean id="myFirstC" class="com.app.C">

    <property name="myList" ref="myList1"></property>

</bean>



<bean id="mySecondC" class="com.app.C">

    <property name="myList" ref="myList2"></property>

</bean>

This defines two beans myFirstC and mySecondC, containing the beans a, b and d, e respectively. So, in Java, you need two @Bean methods creating the same C beans:

 @Configuration

 public class Config {

     @Bean

     public C myFirstC(A a, B b) {

         return new C(Arrays.asList(a, b));

     }





     @Bean

     public C mySecondC(D d, E e) {

         return new C(Arrays.asList(d, e));

     }

 }