Spring Bean Compilation issue

Question

I am messing around and trying out some sample spring code. In this instance i am trying to create a string and use it inside another bean. the other bean sets the string in a class and then when i call that class hopefully it should print out the message. however, i get an error message. Please could someone suggest what might be wrong here?

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

SetterMessage message = (SetterMessage) applicationContext.getBean("setStringFromBean");
System.out.println(message.getMessage()); 
}

public class SetterMessage {

    private String message = null;
    /**
     * Gets message.
     */
    public String getMessage() {
        return message;
    }

    /**
     * Sets message.
     */
    public void setMessage(String message) {
        this.message = message;
    }
}

<bean id="createString" class="java.lang.String">
<constructor-arg value="Hello from a bean"</constructor-arg>
</bean>

<bean id="setStringFromBean" class="SetterMessage">
    <property name="message" ref="createString" />
</bean>

the error is

Oct 23, 2012 8:36:58 PM org.springframework.context.support.AbstractApplicationContext prepareRefresh INFO: Refreshing org.springframework.context.support.ClassPathXmlApplicationContext@4447393f: startup date [Tue Oct 23 20:36:58 BST 2012]; root of context hierarchy Oct 23, 2012 8:36:58 PM org.springframework.beans.factory.xml.XmlBeanDefinitionReader loadBeanDefinitions INFO: Loading XML bean definitions from class path resource [MyConfig.xml] Oct 23, 2012 8:36:58 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@643ae941: defining beans [defaultMessage,constructorBean,setterMessage]; root of factory hierarchy Exception in thread "main" org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named 'setStringFromBean' is defined at org.springframework.beans.factory.support.DefaultListableBeanFactory.getBeanDefinition(DefaultListableBeanFactory.java:549) at org.springframework.beans.factory.support.AbstractBeanFactory.getMergedLocalBeanDefinition(AbstractBeanFactory.java:1095) at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:277) at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:193) at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1106) at Main.main(Main.java:13)

Answer 1

You are looking up a bean by name, but you haven't set its name.

Try:

<bean id="setStringFromBean" name="setStringFromBean" class="SetterMessage">
  <property name="message" ref="createString" />
</bean>

Answer 2

I had an erroneous comment tag in the xml file and therfore it was not being parsed properly

Answer 3

You need to create a constructor to set the "message" property because indirectly you are telling the container to set the "message" property with the help of constructor. So without creating constructor, "message" property value cannot be set. Just do as follows :

public SetterMessage(String message) {
    this.message = message;

}