Question

I have defined a with some “common” values. How can I extend the common list by additional values to various new beans?

<util:list id="myCommonList" list-class="java.util.LinkedList">
 <bean .../>
 <bean .../>
 <bean .../>
 <bean .../>
</util:list>


<bean id="extension" parent="myCommonList">
  <bean ref="additionalValue"/>
</bean>

Will this overwrite the list or extend it?

Answer 1

You can do it, but not using <util:list>, which is just a convenience syntax. The container does provide a “collection merging” function, but you have to use the “old” style:

<bean id="parent" class="org.springframework.beans.factory.config.ListFactoryBean">
    <property name="sourceList">
        <list>
            <value>X</value>
        </list>
    </property>
</bean>

<bean id="child" parent="parent" class="org.springframework.beans.factory.config.ListFactoryBean">
    <property name="sourceList">
        <list merge="true">
            <value>Y</value>
        </list>
    </property>
</bean>