Spring Collections (List, Set, M

Spring examples to show you how to inject values into collections type (List, Set, Map, and Properties). 4 major collection types are supported :

• List – <list/>
• Set – <set/>
• Map – <map/>
• Properties – <props/>

Spring beans

A Customer object, with four collection properties.

package com.mkyong.common;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;
public class Customer { 
    private List<Object> lists; 
    private Set<Object> sets; 
    private Map<Object, Object> maps; 
    private Properties pros; 
    //...
}

See different code snippets to declare collection in bean configuration file.

1. List example

<property name="lists"> 
    <list> 
        <value>1</value> 
        <ref bean="PersonBean" /> 
        <bean class="com.mkyong.common.Person"> 
            <property name="name" value="mkyongList" /> 
            <property name="address" value="address" /> 
            <property name="age" value="28" /> 
         </bean> 
    </list> 
</property>

2. Set example

<property name="sets"> 
    <set> 
        <value>1</value> 
        <ref bean="PersonBean" /> 
        <bean class="com.mkyong.common.Person"> 
            <property name="name" value="mkyongSet" /> 
            <property name="address" value="address" /> 
            <property name="age" value="28" /> 
        </bean> 
    </set> 
</property>

3. Map example

<property name="maps"> 
    <map> 
        <entry key="Key 1" value="1" /> 
        <entry key="Key 2" value-ref="PersonBean" /> 
        <entry key="Key 3"> 
             <bean class="com.mkyong.common.Person"> 
                <property name="name" value="mkyongMap" /> 
                <property name="address" value="address" /> 
                <property name="age" value="28" /> 
            </bean> 
        </entry> 
    </map> 
</property>

4. Properties example

<property name="pros"> 
    <props> 
         <prop key="admin">admin@nospam.com</prop> 
        <prop key="support">support@nospam.com</prop> 
    </props> 
</property>

Full Spring’s bean configuration file.

<beans xmlns="http://www.springframework.org/schema/beans" 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-2.5.xsd"> <bean id="CustomerBean" class="com.mkyong.common.Customer"> <!-- java.util.List --> <property name="lists"> <list> <value>1</value> <ref bean="PersonBean" /> <bean class="com.mkyong.common.Person"> <property name="name" value="mkyongList" /> <property name="address" value="address" /> <property name="age" value="28" /> </bean> </list> </property> <!-- java.util.Set --> <property name="sets"> <set> <value>1</value> <ref bean="PersonBean" /> <bean class="com.mkyong.common.Person"> <property name="name" value="mkyongSet" /> <property name="address" value="address" /> <property name="age" value="28" /> </bean> </set> </property> <!-- java.util.Map --> <property name="maps"> <map> <entry key="Key 1" value="1" /> <entry key="Key 2" value-ref="PersonBean" /> <entry key="Key 3"> <bean class="com.mkyong.common.Person"> <property name="name" value="mkyongMap" /> <property name="address" value="address" /> <property name="age" value="28" /> </bean> </entry> </map> </property> <!-- java.util.Properties --> <property name="pros"> <props> <prop key="admin">admin@nospam.com</prop> <prop key="support">support@nospam.com</prop> </props> </property> </bean> <bean id="PersonBean" class="com.mkyong.common.Person"> <property name="name" value="mkyong1" /> <property name="address" value="address 1" /> <property name="age" value="28" /> </bean></beans>

Run it…

package com.mkyong.common;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class App { 
    public static void main( String[] args ) { 
        ApplicationContext context = new ClassPathXmlApplicationContext("SpringBeans.xml"); 
        Customer cust = (Customer)context.getBean("CustomerBean"); 
       System.out.println(cust); }}

##Output

Customer [

lists=[
1,
Person [address=address 1, age=28, name=mkyong1],
Person [address=address, age=28, name=mkyongList]
],

maps={
key 1=1,
key 2=Person [address=address 1, age=28, name=mkyong1],
key 3=Person [address=address, age=28, name=mkyongMap]
},

pros={admin=admin@nospam.com, support=support@nospam.com},

sets=[
1,
Person [address=address 1, age=28, name=mkyong1],
Person [address=address, age=28, name=mkyongSet]]
]