Cannot find class [main.java.OutputHelper] for bean with name 'OutputHelper' defined in class path resource - spring

Question

I am new to Spring. I am creating simple project in which I just call generateOutout() method using beans.
IOutputGenerator Interface:
package mian.java;
public interface IOutputGenerator {
public void generateOutput();
}
CsvOutputGenerator.java (implements IOutputGenerator ):
package mian.java;
public class CsvOutputGenerator implements IOutputGenerator{
public void generateOutput(){
System.out.println("Csv Output Generator");
}
}
JsonOutputGenerator.java (implements IOutputGenerator ):
package mian.java;
public class JsonOutputGenerator implements IOutputGenerator {
public void generateOutput(){
System.out.println("Json Output Generator");
}
}
OutputHelper.java:
package mian.java;
public class OutputHelper {
IOutputGenerator outputGeneratorCsv;
IOutputGenerator outputGeneratorJson;
public void generateOutput(){
outputGeneratorCsv.generateOutput();
outputGeneratorJson.generateOutput();
}
public void setOutputGenerator(IOutputGenerator outputGeneratorCsv,IOutputGenerator outputGeneratorJson){
this.outputGeneratorCsv = outputGeneratorCsv;
this.outputGeneratorJson = outputGeneratorJson;
}
}
AppViaSpring.java (Main class):
package mian.java;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class AppViaSpring {
public static void main( String[] args )
{
ApplicationContext context =
new ClassPathXmlApplicationContext(new String[] {"Spring-Common.xml"});
OutputHelper output = (OutputHelper)context.getBean("OutputHelper");
output.generateOutput();
}
}
Spring-Common.xml (Bean Class in main.resources package):
<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-2.5.xsd">
<bean id="OutputHelper" class="main.java.OutputHelper">
<property name="outputGeneratorCsv" ref="CsvOutputGenerator" />
</bean>
<bean id="CsvOutputGenerator" class="main.java.CsvOutputGenerator" />
<bean id="JsonOutputGenerator" class="main.java.JsonOutputGenerator" />
</beans>
and Error is :
Exception in thread "main" org.springframework.beans.factory.CannotLoadBeanClassException: Cannot find class [main.java.OutputHelper] for bean with name 'OutputHelper' defined in class path resource [Spring-Common.xml]; nested exception is java.lang.ClassNotFoundException: main.java.OutputHelper
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1141)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.predictBeanType(AbstractAutowireCapableBeanFactory.java:524)
at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:1177)
at org.springframework.beans.factory.support.AbstractBeanFactory.isFactoryBean(AbstractBeanFactory.java:758)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:422)
at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:728)
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:380)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:139)
at org.springframework.context.support.ClassPathXmlApplicationContext.<init>(ClassPathXmlApplicationContext.java:93)
at mian.java.AppViaSpring.main(AppViaSpring.java:10)
Caused by: java.lang.ClassNotFoundException: main.java.OutputHelper
at java.net.URLClassLoader$1.run(URLClassLoader.java:366)
at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
at org.springframework.util.ClassUtils.forName(ClassUtils.java:211)
at org.springframework.beans.factory.support.AbstractBeanDefinition.resolveBeanClass(AbstractBeanDefinition.java:385)
at org.springframework.beans.factory.support.AbstractBeanFactory.resolveBeanClass(AbstractBeanFactory.java:1138)
... 9 more

Answer 1

you forgot to add the JsonOutputGenerator bean for OutputHelper
try this:
<bean id="OutputHelper" class="main.java.OutputHelper">
<property name="outputGeneratorCsv" ref="CsvOutputGenerator" />
<property name="outputGeneratorJson" ref="JsonOutputGenerator" />
</bean>
note you can also use context.getBean(OutputHelper.class), no casting will be required
edit:
on the further look at the problem. The setter you are using has two arguments which violates javaBean convention. There are few options.
1. You simply pass the map to the setter.
2. Create setter for each generator field.
3. You inject outputGeneratorCsv and outputGeneratorJson in the constructor - i would recommend that. In that case you would have to add constructor with two arguments (like your setter method) and modify the spring context xml to something like that:
<bean id="OutputHelper" class="main.java.OutputHelper">
<constructor-arg ref="outputGeneratorCsv"/>
<constructor-arg ref="outputGeneratorJson"/>
</bean>
here also some more info, why to use constructor injections:
We usually advise people to use constructor injection for all mandatory collaborators and setter injection for all other properties. Again, constructor injection ensures all mandatory properties have been satisfied, and it is simply not possible to instantiate an object in an invalid state (not having passed its collaborators). In other words, when using constructor injection you do not have to use a dedicated mechanism to ensure required properties are set (other than normal Java mechanisms).
Setter injection versus constructor injection