Spring Collection Merging

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Spring Collection Merging
Posted on: August 19, 2010 at 12:00 AM

In this tutorial you will see an example of spring collection merging.

Spring Collection Merging

The merging of collection is allowed in the Spring 2.0. A parent-style like <list/>, <map/>, <set/> or <pros/> element can have child-style <list/>, <map/>, <set/> or <pros/> element which inherit and overrides the values from the parent collection. For collection merging you need to specify merge=true attribute on the <props/> element of child bean definition. Note you cannot merge Map and List collection type.

CollegeBean.java


package collection.merge.example;



import java.util.Properties;



public class CollegeBean {

  private Properties pros;



  public Properties getPros() {

    return pros;

  }



  public void setPros(Properties pros) {

    this.pros = pros;

  }



  @Override

  public String toString() {

    return "College [Props=" + pros + "]";

  }

}

ProsMain.java


package collection.merge.example;



import org.springframework.beans.factory.BeanFactory;

import org.springframework.context.support.ClassPathXmlApplicationContext;



public class PropsMain {

  public static void main(String[] args) {

    BeanFactory beanfactory = new ClassPathXmlApplicationContext(

        "context.xml");

    CollegeBean coll = (CollegeBean) beanfactory.getBean("child");

    System.out.println(coll);

  }

}

context.xml


	<bean id="parent" abstract="true" 
class="collection.merge.example.CollegeBean">

  <property name="pros">

    <props>

      <prop key="Year">25</prop>

      <prop key="NickName">Raj</prop>

    </props>

  </property>

</bean>



<bean id="child" parent="parent" >

  <property name="pros">

    <props merge="true">

      <prop key="Roll">101</prop>

      <prop key="Name">Rohit Raj</prop>

    </props>  

  </property>

</bean>  

</beans>

When you run this application it will display output as shown below:

College [Props={Name=Rohit Raj, Roll=101, Year=25, NickName=Raj}]

Download this example code

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