Create List and Map Beans in Spring XML

Overview #

In this article, we’ll explore how to create lists and maps in the Spring Framework using XML configuration.

Util Namespace #

First, we need to make sure that the Spring util namespace is imported at the top of the file.

<?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: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/util 
   		   http://www.springframework.org/schema/util/spring-util.xsd">
</beans>

Creating Lists #

We can define a list bean as follows:

<util:list id="namesList" value-type="java.lang.String">
  <value>Amir</value>
  <value>Arnie</value>
  <value>Beth</value>
  <value>Lucy</value>
</util:list>

The value-type attribute is optional but useful to include since it makes it clear what types of objects the list contains.

The default list implementation is ArrayList. To use a different implementation, include the list-class attribute:

<util:list id="namesList" list-class="java.util.LinkedList" value-type="java.lang.String">
  <value>Amir</value>
  <value>Arnie</value>
  <value>Beth</value>
  <value>Lucy</value>
</util:list>

We can reference other beans in our list as well:

<bean id="maxLengthValidator" class="com.codebyamir.data.Validator" />
<bean id="formatValidator" class="com.codebyamir.data.Validator" />

<util:list id="validators" value-type="com.codebyamir.data.Validator">
  <ref bean="maxLengthValidator"/>
  <ref bean="formatValidator"/>
</util:list>

Creating Maps #

Similarly, we can define a map as follows:

<util:map id="responsiveImageFormats" map-class="java.util.HashMap" key-type="java.lang.String" value-type="java.lang.Integer">
  <entry key="widescreen" value="1200"/>
  <entry key="desktop" value="992"/>
  <entry key="tablet" value="768"/>
  <entry key="mobile" value="480"/>
</util:map>