Setter Injection with Map Example
In this example, we are using map as the answer for a question that have answer as the key and username as the value. Here, we are using key and value pair both as a string.
Like previous examples, it is the example of forum where one question can have multiple answers.
Question.java
This class contains three properties, getters & setters and displayInfo() method to display the information.
package com.springexample;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;
public class Question {
private int id;
private String name;
private Map<String,String> answers;
//getters and setters
public void displayInfo(){
System.out.println("question id:"+id);
System.out.println("question name:"+name);
System.out.println("Answers....");
Set<Entry<String, String>> set=answers.entrySet();
Iterator<Entry<String, String>> itr=set.iterator();
while(itr.hasNext()){
Entry<String,String> entry=itr.next();
System.out.println("Answer:"+entry.getKey()+" Posted By:"+entry.getValue());
}
}
}
applicationContext.xml
The entry attribute of map is used to define the key and value information.
<?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:p="http://www.springframework.org/schema/p"
xsi:schemaLocation="http://www.springframework.org/schema/beans
http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">
<bean id="q" class="com.springexample.Question">
<property name="id" value="1"></property>
<property name="name" value="What is Java?"></property>
<property name="answers">
<map>
<entry key="Java is a programming language" value="Sonoo Jaiswal"></entry>
<entry key="Java is a Platform" value="Sachin Yadav"></entry>
</map>
</property>
</bean>
</beans>
Test.java
This class gets the bean from the applicationContext.xml file and calls the displayInfo() method.
package com.springexample;
import org.springframework.beans.factory.BeanFactory;
import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.ClassPathResource;
import org.springframework.core.io.Resource;
public class Test {
public static void main(String[] args) {
Resource r=new ClassPathResource("applicationContext.xml");
BeanFactory factory=new XmlBeanFactory(r);
Question q=(Question)factory.getBean("q");
q.displayInfo();
}
}