idref gives exception

[omkar patkar]

Hello Friends....

I am trying a simple program to see how idref works ... but i am getting exception, so wondering how it works and when to use it?
Please help

Class B: -

package org.spring.tut.helloworld;

public class B {

	private int i;

	public int getI() {
		return i;
	}

	public void setI(int i) {
		this.i = i;
	}

	/*public String toString() {
		// TODO Auto-generated method stub
		return this.i+"";
	}*/
	
	
}

and class A: -

package org.spring.tut.helloworld;

package org.spring.tut.helloworld;

public class A {

	private B objOfB;

	public B getObjOfB() {
		return objOfB;
	}

	public void setObjOfB(B objOfB) {
		this.objOfB = objOfB;
	}

	public String toString() {
		// TODO Auto-generated method stub
		
		String s = "A is "+this.hashCode()+" and it contains b as "+this.objOfB;
		return s;
	}
	
	
}

the spring 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" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd"> <bean id="b" class="org.spring.tut.helloworld.B"> <property name="i"> <value>234</value> </property> </bean> <!-- bean id="a" class="org.spring.tut.helloworld.A"> <property name="objOfB" ref="b"/> </bean--> <!-- bean id="a1" class="org.spring.tut.helloworld.A"> <property name="objOfB" value="b"/> </bean--> <bean id="a2" class="org.spring.tut.helloworld.A"> <property name="objOfB"> <idref bean="b"/> </property> </bean> </beans>

and my Tester class: -

package org.spring.tut.helloworld.testarea;

import org.spring.tut.helloworld.A;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class DepInjectTester {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		// TODO Auto-generated method stub

		ApplicationContext appcontext = new ClassPathXmlApplicationContext("DepInject.xml");
		
		/*A a = (A)appcontext.getBean("a");
		System.out.println(a);*/
		
		
		/*A a1 = (A)appcontext.getBean("a1");
		System.out.println(a1);*/
		
		
		A a2 = (A)appcontext.getBean("a2");
		System.out.println(a2);
	}

}

i am getting following exception ....

Feb 10, 2013 11:06:14 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh
INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@933bcb: startup date [Sun Feb 10 23:06:14 IST 2013]; root of context hierarchy
Feb 10, 2013 11:06:14 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions
INFO: Loading XML bean definitions from class path resource [DepInject.xml]
Feb 10, 2013 11:06:14 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons
INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@faadb1: defining beans [b,a2]; root of factory hierarchy
Feb 10, 2013 11:06:15 PM org.springframework.beans.factory.support.DefaultSingletonBeanRegistry destroySingletons
INFO: Destroying singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@faadb1: defining beans [b,a2]; root of factory hierarchy
Exception in thread "main" org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'a2' defined in class path resource [DepInject.xml]: Initialization of bean failed; nested exception is org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'java.lang.String' to required type 'org.spring.tut.helloworld.B' for property 'objOfB'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [org.spring.tut.helloworld.B] for property 'objOfB': no matching editors or conversion strategy found
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:529)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:458)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:294)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:225)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:291)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:605)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:932)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:479)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:83)
at org.spring.tut.helloworld.testarea.DepInjectTester.main(DepInjectTester.java:15)
Caused by: org.springframework.beans.ConversionNotSupportedException: Failed to convert property value of type 'java.lang.String' to required type 'org.spring.tut.helloworld.B' for property 'objOfB'; nested exception is java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [org.spring.tut.helloworld.B] for property 'objOfB': no matching editors or conversion strategy found
at org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:465)
at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:496)
at org.springframework.beans.BeanWrapperImpl.convertForProperty(BeanWrapperImpl.java:490)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.convertForProperty(AbstractAutowireCapableBeanFactory.java:1417)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.applyPropertyValues(AbstractAutowireCapableBeanFactory.java:1376)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1129)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:519)
... 11 more
Caused by: java.lang.IllegalStateException: Cannot convert value of type [java.lang.String] to required type [org.spring.tut.helloworld.B] for property 'objOfB': no matching editors or conversion strategy found
at org.springframework.beans.TypeConverterDelegate.convertIfNecessary(TypeConverterDelegate.java:264)
at org.springframework.beans.BeanWrapperImpl.convertIfNecessary(BeanWrapperImpl.java:450)
... 17 more

.... how does idref work ? .... i refered to the spring documentation reference but no explict explanation of the same !

[Mark Spritzler]

No one uses <idRef> so don't worry about it.

Mark