Spring Injection getting null pointer Exception

Question

I get a null pointer exception when trying to inject an object. Here is my code:

<context-param>
<param-name>contextConfigLocation</param-name>
<param-value>
/WEB-INF/applicationContext.xml
</param-value>
 </context-param>'

ApplicationContext.XML

<bean id="accessDao" 
 Class="org.springframework.transaction.interceptor.TransactionProxyFactoryBean" 
  autowire-candidate="true">
  <property name="transactionManager" ref="txManager" />   
  <property name="target" ref="accessDaoTarget" />   
   <property name="transactionAttributes">   
   <props>   
  <prop key="*">PROPAGATION_REQUIRED</prop>   
   </props>   
  </property>   

</bean>   '

CommonBean

import com.domain.dao.IDao;
@Named
public class CommonBean implements Serializable{

/**
 * 
 */

private static final long serialVersionUID = 1L;
@Inject
private IDao accessDao;


public IDao getAccessDao()

      {
        return accessDao;
      }

 public void setAccessDao(IDao accessDao)
  {
    this.accessDao = accessDao;
  }

}

Do you have "context:component-scan" defined in your applicationContext.xml context file. — Jayamohan
– Jayamohan, Commented Feb 22, 2013 at 6:32
s..Here it is <context:component-scan base-package="com.myjsf.appl.CommonBean" /> — Karthik
– Karthik, Commented Feb 22, 2013 at 6:38

Sudhakar · Accepted Answer · 2013-02-22 06:54:09Z

0

The reason i suppose is because the component scan should include all the files that annotated by Spring. So for this to work , broaden the scope of packages to scan.

change from

<context:component-scan base-package="com.myjsf.appl.CommonBean" />

to

 <context:component-scan base-package="com.domain,com.myjsf" />

answered Feb 22, 2013 at 6:54

Sudhakar

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3 Comments

Karthik Over a year ago

Thanks for your immediately reply Mr.sudhakar..I tried it but still getting the same exception

Karthik Over a year ago

Hi mohan he s referring two different packages seperated by comma.

Sudhakar Over a year ago

Can you make sure you add all packages that use spring annotation to the <context:component-scan> tag, also can you post your applicationContext.xml and your package structure

reis · Accepted Answer · 2013-02-22 18:29:17Z

-1

I think the reason is because you are refering to an "accessDao" bean which implements a IDAO interface. The bean accessDao declared on applicationContext.xml is of type org.springframework.transaction.interceptor.TransactionProxyFactoryBean which implements the BeanFactoryAware interface and NOT the IDAO interface.

As so spring will not recognize the bean you are trying to inject (IDAO accessDAO) and your property will not be initialized.

answered Feb 22, 2013 at 18:29

reis

1

1 Comment

madth3 Over a year ago

Wrong. That bean will implement interfaces defined by the target specified.

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