@Qualifier Annotation in spring

you can have more than one bean of same type in your XML configuration but you want to autowire only one of them ,so @Qualifier removes confusion created by @Autowired by declaring exactly which bean is to autowired.

Example:

For configuring spring in your eclipse ide please refer hello world example

1.Country.java:

This is simple pojo class having some attributes so here country has name and object of Capital class.

Create Country.java under package org.arpit.javapostsforlearning.Copy following content into Country.java.

package org.arpit.javapostsforlearning;
import org.springframework.beans.factory.annotation.Autowired;
public class Country {

    String countryName;
    @Autowired
    @Qualifier("capitalA") 
    Capital capital;
    public String getCountryName() {
        return countryName;
    }
    public void setCountryName(String countryName) {
        this.countryName = countryName;
    }
    public Capital getCapital() {
        return capital;
    }
}

2.Capital.java

This is also simple pojo class having one attribute called "capitalName".

Create Capital.java under package org.arpit.javapostsforlearning.java.Above Country class contains object of this class.Copy following content into Capital.java

package org.arpit.javapostsforlearning;

public class Capital {

    String capitalName;

    public String getCapitalName() {
        return capitalName;
    }

    public void setCapitalName(String capitalName) {
        this.capitalName = capitalName;
    }
}

3.QualifierAnnotationInSpringMain.java

This class contains main function.Create QualifierAnnotationInSpringMain.java under package org.arpit.javapostsforlearning.Copy following content into QualifierAnnotationInSpringMain.java

 package org.arpit.javapostsforlearning;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class QualifierAnnotationInSpringMain{

    public static void main(String[] args) {
        ApplicationContext appContext = new ClassPathXmlApplicationContext("ApplicationContext.xml");

        Country countryObj = (Country) appContext.getBean("CountryBean");
        String countryName=countryObj.getCountryName();
        Capital capital=countryObj.getCapital();
        String capitalName=capital.getCapitalName();
        System.out.println(capitalName+" is capital of "+countryName);
       
    }
}

4.ApplicationContext.xml

<?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"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context-3.0.xsd">
 <context:annotation-config/>
 <bean id="CountryBean" class="org.arpit.javapostsforlearning.Country">
  <property name="countryName" value="India" />
 </bean>
 <bean id="capitalA" class="org.arpit.javapostsforlearning.Capital">
  <property name="capitalName" value="Delhi" />
 </bean>
 <bean id="capitalB" class="org.arpit.javapostsforlearning.Capital">
  <property name="capitalName" value="Mumbai" />
 </bean>
</beans>

As you can note here we are having two beans of same type.In Country.java we have used @Qualifier("capitalA") it means we want to autowire capital property of country with bean id="capitalA" in XML configuration file.

5.Run it:

When you will run above application,you will get following as output.

Delhi is capital of India